学步园

Though Rujia Liu usually sets hard problems for contests (for example, regional contests like Xi'an 2006, Beijing 2007 and Wuhan 2009, or UVa OJ contests like Rujia Liu's Presents 1 and 2),
he occasionally sets easy problem (for example, 'the Coco-Cola Store' in UVa OJ), to encourage more people to solve his problems

Given an array, your task is to find the k-th occurrence (from left to right) of an integer v. To make the problem more difficult (and interesting!), you'll have to answer m such queries.

Input

There are several test cases. The first line of each test case contains two integers n, m(1<=n,m<=100,000), the number of elements in the array, and the number of queries. The next line contains n positive integers not larger than 1,000,000. Each of the following
m lines contains two integer k and v (1<=k<=n, 1<=v<=1,000,000). The input is terminated by end-of-file (EOF). The size of input file does not exceed 5MB.

Output

For each query, print the 1-based location of the occurrence. If there is no such element, output 0 instead.

Sample Input

8 4
1 3 2 2 4 3 2 1
1 3
2 4
3 2
4 2

Output for the Sample Input

2
0
7
0

map<int, vector<int> > mp;

#include <cstdio>
#include <set>
#include <map>
#include <vector>
#include <iostream>
using namespace std;

map<int, vector<int> > mp;
int n, m;
int k, v;

int main()
{
    while(~scanf("%d%d",&n, &m)){
        mp.clear();
        for(int i=1; i<=n; ++i){
            scanf("%d",&v);
            if(!mp.count(v)) mp[v] = vector<int>();
            mp[v].push_back(i);
        }

        while(m--){
            scanf("%d%d",&k, &v);
            if(!mp.count(v) || mp[v].size()<k){
                printf("0\n");
            }else {
                printf("%d\n", mp[v][k-1]);
            }
        }

    }
    return 0;
}