#include<bits/stdc++.h>
using namespace std;
int main()
{
    int m,i,n,s=-1;
    int x[100];
    cin>>m;
    for(i=0;i<m;i++){
        cin>>x[i];
    }
    cin>>n;
    for(i=0;i<m;i++){
        if(x[i]==n){
            s=i+1;
            break;
        }
    }
    cout<<s;
}
/**************************************************************
	Problem: 1154
	User: wangyiyang
	Language: C++
	Result: Accepted
	Time:20 ms
	Memory:2072 kb
****************************************************************/