#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    cin>>n;
    int arr[n];
    for(int i=0;i,n;i++)
    {
        cin>>arr[i];
        
    }
    int target;
    cin>>target;
     int count=0;
    for(int i=0;i<n;i++)
    {
        if(arr[i]==target)
        {
            count++;
            if(count==2)
            {
                cout<<i;
                return 0;
            }
          
        }
    }
    cout<<target<<"key not found"<<endl;
    
    
}