#include <bits/stdc++.h>
using namespace std;
int main(){
    int m;
    long long a[100],n;
    cin>>m;
    for(int i=0;i<m;i++){
        cin>>a[i];
    }
    cin>>n;
    for(int i=0;i<m;i++){
        if(a[i]==n){
            cout<<i+1;
            return 0;
        }
    }
    cout<<"-1";
}
/**************************************************************
	Problem: 1154
	User: wngjinming
	Language: C++
	Result: Accepted
	Time:18 ms
	Memory:2072 kb
****************************************************************/