11991 - Easy Problem from Rujia Liu?

#include <bits/stdc++.h>
#define md 1000010
long int a[md];
 vector <long int> vx[md];
using namespace std;
int main()
{
    long int n , m;
    while(cin >> n >> m)
    {
 
        long int p;
       
 
        vector <long int> vc;
 
        for(int i = 0; i < n; i++)
        {
           cin >> a[i];
 
           vx[a[i]].push_back(i + 1);
        }
 
    long int a , b;
         for(int i=0;i<m;i++)
        {
            cin >> a >> b;
 
            if(vx[b].size() < a)
                printf("0\n");
            else
                printf("%ld\n",vx[b][a-1]);
        }
       for(int i = 0; i < md; i++)
       {
           vx[i].clear();
       }
 
    }
}