UVa 11991 Easy Problem from Rujia Liu?

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

void scan(int& x)
{
char c;
while(c = getchar(), c < '0' || c > '9');
x = c - '0';
while(c = getchar(), c >= '0' && c <= '9') x = x*10 + c - '0';
}

const int maxn = 100000 + 10;

int main()
{
//freopen("in.txt", "r", stdin);

int n, m;
while(scanf("%d%d", &n, &m) == 2)
{
map<int, vector<int> > pos;
for(int i = 1; i <= n; i++)
{
int x;
scan(x);
pos[x].push_back(i);
}
for(int i = 0; i < m; i++)
{
int k, v;
scan(k); scan(v);
if(k <= pos[v].size()) printf("%d\n", pos[v][k-1]);
else printf("0\n");
}
}

return 0;
}