【題目敘述】https://cses.fi/problemset/task/1687/
#include <iostream>
using namespace std;
int n, q, a, b, p[200005][20];
int main() {
cin >> n >> q;
for (int i = 2; i <= n; i++){
cin >> p[i][0];
}
for (int i = 1; i < 20; i++){
for (int j = 1; j <= n; j++){
p[j][i] = p[p[j][i-1]][i-1];
}
}
while (q--){
cin >> a >> b;
for (int i = 0; i < 20; i++){
if (b & (1<<i)) a = p[a][i];
}
if (!a) cout << -1 << "\n";
else cout << a << "\n";
}
}