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Cod sursa(job #984262)
#include <cstdio>
#include <algorithm>
#include <vector>
using namespace std;
struct Query {
int p,num;
Query() {
p=num=0;
}
Query(int a,int b) {
p=a;
num=b;
}
};
const int MAX_N = 500100;
const int MAX_M = 500100;
vector<int> A[MAX_N];
vector<Query> Q[MAX_N];
int sol[MAX_M];
int viz[MAX_N];
int n,m;
int st[MAX_N];
void bfs(int nod) {
st[++st[0]]=nod;
viz[nod]=1;
for(vector<Query>::iterator it=Q[nod].begin(); it!= Q[nod].end(); it++) {
if(it->p>=st[0])
sol[it->num]=0;
else
sol[it->num]=st[st[0]-it->p];
}
for( vector<int>::iterator it=A[nod].begin(); it!= A[nod].end();it++) {
bfs(*it);
}
st[0]--;
}
int main() {
freopen("stramosi.in","r",stdin);
freopen("stramosi.out","w",stdout);
scanf("%d%d",&n,&m);
for(int i=1; i<=n; i++) {
int a;
scanf("%d",&a);
if(a) {
A[a].push_back(i);
}
}
for(int i=1; i<=m; i++) {
int p,q;
scanf("%d%d",&q,&p);
Q[q].push_back(Query(p,i));
}
for(int i=1;i<=n;i++)
if(!viz[i])
bfs(i);
for(int i=1;i<=m;i++)
printf("%d\n",sol[i]);
return 0;
}