#include <iostream>
using namespace std;

int main()
{
    int n;
    int i;
    char s;
    char a[1001];
    cin>>n;

    for (i = 0; i<n*2; i++)
        cin>>a[i];
    cin>>s;
    for (i=0; i<n*2; i++)
    {


        if (s == a[i] && i % 2 == 0)
           cout<<a[i]<<a[i+1]<<endl;
    }


    system("pause");
    return 0;
}

a[1001] should be a[2000] at least;

Thanks )))