UVA - 11991 - Easy Problem from Rujia Liu?

#include <stdio.h>
#include <vector>

using namespace std;

vector<int> arr[1000001];
int main()
{

    int x,y,z,num,occ;
    while(scanf("%d %d",&x,&y)==2){
        for ( int i = 0; i < 1000001; i++ ) {
            arr[i].clear ();
        }
        for(int i=0;i<x;i++){
            scanf("%d",&z);
            arr[z].push_back (i + 1);
        }
        for(int i=0;i<y;i++){
            scanf ("%d %d", &occ, &num);
             if ( arr[num].size()< occ ) {
                printf("0\n");
             }
            else{
                printf("%d\n",arr [num] [occ - 1]);
            }
        }
    }
}