#line 1 "verify/tree/LC_jump_on_tree.test.cpp"
#define PROBLEM "https://judge.yosupo.jp/problem/jump_on_tree"
#line 2 "template/template.hpp"
#include <bits/stdc++.h>
using namespace std ;
#line 2 "template/macro.hpp"
#define rep(i, a, b) for (int i = (a); i < (int)(b); i++)
#define rrep(i, a, b) for (int i = (int)(b) - 1; i >= (a); i--)
#define ALL(v) (v).begin(), (v).end()
#define UNIQUE(v) sort(ALL(v)), (v).erase(unique(ALL(v)), (v).end())
#define SZ(v) (int)v.size()
#define MIN(v) *min_element(ALL(v))
#define MAX(v) *max_element(ALL(v))
#define LB(v, x) int(lower_bound(ALL(v), (x)) - (v).begin())
#define UB(v, x) int(upper_bound(ALL(v), (x)) - (v).begin())
#define YN(b) cout << ((b) ? "YES" : "NO") << "\n";
#define Yn(b) cout << ((b) ? "Yes" : "No") << "\n";
#define yn(b) cout << ((b) ? "yes" : "no") << "\n";
#line 6 "template/template.hpp"
#line 2 "template/util.hpp"
using uint = unsigned int ;
using ll = long long int ;
using ull = unsigned long long ;
using i128 = __int128_t ;
using u128 = __uint128_t ;
template < class T , class S = T >
S SUM ( const vector < T >& a ) {
return accumulate ( ALL ( a ), S ( 0 ));
}
template < class T >
inline bool chmin ( T & a , T b ) {
if ( a > b ) {
a = b ;
return true ;
}
return false ;
}
template < class T >
inline bool chmax ( T & a , T b ) {
if ( a < b ) {
a = b ;
return true ;
}
return false ;
}
template < class T >
int popcnt ( T x ) {
return __builtin_popcountll ( x );
}
template < class T >
int topbit ( T x ) {
return ( x == 0 ? - 1 : 63 - __builtin_clzll ( x ));
}
template < class T >
int lowbit ( T x ) {
return ( x == 0 ? - 1 : __builtin_ctzll ( x ));
}
#line 8 "template/template.hpp"
#line 2 "template/inout.hpp"
struct Fast {
Fast () {
cin . tie ( nullptr );
ios_base :: sync_with_stdio ( false );
cout << fixed << setprecision ( 15 );
}
} fast ;
ostream & operator << ( ostream & os , __uint128_t x ) {
char buf [ 40 ];
size_t k = 0 ;
while ( x > 0 ) buf [ k ++ ] = ( char )( x % 10 + '0' ), x /= 10 ;
if ( k == 0 ) buf [ k ++ ] = '0' ;
while ( k ) os << buf [ -- k ];
return os ;
}
ostream & operator << ( ostream & os , __int128_t x ) {
return x < 0 ? ( os << '-' << ( __uint128_t )( - x )) : ( os << ( __uint128_t ) x );
}
template < class T1 , class T2 >
istream & operator >> ( istream & is , pair < T1 , T2 >& p ) {
return is >> p . first >> p . second ;
}
template < class T1 , class T2 >
ostream & operator << ( ostream & os , const pair < T1 , T2 >& p ) {
return os << p . first << " " << p . second ;
}
template < class T >
istream & operator >> ( istream & is , vector < T >& a ) {
for ( auto & v : a ) is >> v ;
return is ;
}
template < class T >
ostream & operator << ( ostream & os , const vector < T >& a ) {
for ( auto it = a . begin (); it != a . end ();) {
os << * it ;
if ( ++ it != a . end ()) os << " " ;
}
return os ;
}
template < class T >
ostream & operator << ( ostream & os , const set < T >& st ) {
os << "{" ;
for ( auto it = st . begin (); it != st . end ();) {
os << * it ;
if ( ++ it != st . end ()) os << "," ;
}
os << "}" ;
return os ;
}
template < class T1 , class T2 >
ostream & operator << ( ostream & os , const map < T1 , T2 >& mp ) {
os << "{" ;
for ( auto it = mp . begin (); it != mp . end ();) {
os << it -> first << ":" << it -> second ;
if ( ++ it != mp . end ()) os << "," ;
}
os << "}" ;
return os ;
}
void in () {}
template < typename T , class ... U >
void in ( T & t , U & ... u ) {
cin >> t ;
in ( u ...);
}
void out () { cout << " \n " ; }
template < typename T , class ... U , char sep = ' ' >
void out ( const T & t , const U & ... u ) {
cout << t ;
if ( sizeof ...( u )) cout << sep ;
out ( u ...);
}
namespace IO {
namespace Graph {
vector < vector < int >> unweighted ( int n , int m , bool directed = false , int offset = 1 ) {
vector < vector < int >> g ( n );
for ( int i = 0 ; i < m ; i ++ ) {
int u , v ;
cin >> u >> v ;
u -= offset , v -= offset ;
g [ u ]. push_back ( v );
if ( ! directed ) g [ v ]. push_back ( u );
}
return g ;
}
template < class T >
vector < vector < pair < int , T >>> weighted ( int n , int m , bool directed = false , int offset = 1 ) {
vector < vector < pair < int , T >>> g ( n );
for ( int i = 0 ; i < m ; i ++ ) {
int u , v ;
T w ;
cin >> u >> v >> w ;
u -= offset , v -= offset ;
g [ u ]. push_back ({ v , w });
if ( ! directed ) g [ v ]. push_back ({ u , w });
}
return g ;
}
} // namespace Graph
namespace Tree {
vector < vector < int >> unweighted ( int n , bool directed = false , int offset = 1 ) {
return Graph :: unweighted ( n , n - 1 , directed , offset );
}
template < class T >
vector < vector < pair < int , T >>> weighted ( int n , bool directed = false , int offset = 1 ) {
return Graph :: weighted < T > ( n , n - 1 , directed , offset );
}
vector < vector < int >> rooted ( int n , bool to_root = true , bool to_leaf = true , int offset = 1 ) {
vector < vector < int >> g ( n );
for ( int i = 1 ; i < n ; i ++ ) {
int p ;
cin >> p ;
p -= offset ;
if ( to_root ) g [ i ]. push_back ( p );
if ( to_leaf ) g [ p ]. push_back ( i );
}
return g ;
}
} // namespace Tree
} // namespace IO
#line 10 "template/template.hpp"
#line 2 "template/debug.hpp"
#ifdef LOCAL
#define debug 1
#define show(...) _show(0, #__VA_ARGS__, __VA_ARGS__)
#else
#define debug 0
#define show(...) true
#endif
template < class T >
void _show ( int i , T name ) {
cerr << '\n' ;
}
template < class T1 , class T2 , class ... T3 >
void _show ( int i , const T1 & a , const T2 & b , const T3 & ... c ) {
for (; a [ i ] != ',' && a [ i ] != '\0' ; i ++ ) cerr << a [ i ];
cerr << ":" << b << " " ;
_show ( i + 1 , a , c ...);
}
#line 2 "tree/tree-jump.hpp"
struct TreeJump {
inline static int topbit ( int x ) {
return ( x == 0 ? - 1 : 31 - __builtin_clz (( unsigned int ) x ));
}
int n ;
vector < vector < int >> g ;
vector < vector < int >> p ;
vector < int > depth ;
TreeJump ( int size ) : n ( size ), g ( size ), p ( size ), depth ( size ) {}
TreeJump ( const vector < vector < int >>& graph ) : n ( graph . size ()), g ( graph ), p ( graph . size ()), depth ( graph . size ()) {
build ();
}
void add_edge ( int u , int v ) {
g [ u ]. push_back ( v );
g [ v ]. push_back ( u );
}
void build () {
stack < int > st ;
st . push ( 0 );
while ( ! st . empty ()) {
int x = st . top ();
st . pop ();
for ( int k = 0 ; k < p [ x ]. size (); k ++ ) {
int y = p [ x ][ k ];
if ( k >= p [ y ]. size ()) break ;
p [ x ]. push_back ( p [ y ][ k ]);
}
int par = p [ x ]. empty () ? - 1 : p [ x ][ 0 ];
for ( auto y : g [ x ]) {
if ( y == par ) continue ;
p [ y ]. push_back ( x );
depth [ y ] = depth [ x ] + 1 ;
st . push ( y );
}
}
}
int ancestor ( int x , int k = 1 ) {
assert ( k >= 0 );
if ( depth [ x ] < k ) return - 1 ;
while ( k > 0 ) {
int l = topbit ( k );
x = p [ x ][ l ];
k ^= 1 << l ;
}
return x ;
}
int lca ( int x , int y ) {
if ( depth [ x ] < depth [ y ]) y = ancestor ( y , depth [ y ] - depth [ x ]);
if ( depth [ x ] > depth [ y ]) x = ancestor ( x , depth [ x ] - depth [ y ]);
if ( x == y ) return x ;
for ( int l = topbit ( depth [ x ]); l >= 0 ; l -- ) {
int ml = min (( int ) p [ x ]. size (), ( int ) p [ y ]. size ()) - 1 ;
if ( ml < l ) l = ml ;
int x1 = p [ x ][ l ];
int y1 = p [ y ][ l ];
if ( x1 != y1 ) x = x1 , y = y1 ;
}
return p [ x ][ 0 ];
}
int dist ( int x , int y ) {
return depth [ x ] + depth [ y ] - depth [ lca ( x , y )] * 2 ;
}
int jump ( int x , int y , int k = 1 ) {
assert ( 0 <= k );
int z = lca ( x , y );
int dx = depth [ x ] - depth [ z ];
int dy = depth [ y ] - depth [ z ];
if ( k <= dx ) return ancestor ( x , k );
int d = dx + dy ;
return k <= d ? ancestor ( y , d - k ) : - 1 ;
}
};
/**
* @brief Tree Jump
* @docs docs/tree/tree-jump.md
*/
#line 5 "verify/tree/LC_jump_on_tree.test.cpp"
int main () {
int n , q ;
in ( n , q );
auto g = IO :: Tree :: unweighted ( n , false , 0 );
auto jump = TreeJump ( g );
while ( q -- ) {
int s , t , i ;
in ( s , t , i );
out ( jump . jump ( s , t , i ));
}
}