#include <bits/stdc++.h>
using namespace std;
int main(){
    int m,n,a[110]={0},i,t=0;
    cin>>m;
    for(i=0;i<m;i++){
        cin>>a[i]; 
    }
    cin>>n;
    for(i=0;i<m;i++){
        if(n==a[i]){
            t=i+1;
            break;
        } 
    }
    if(t>0){
        cout<<t;
    }else{
        cout<<"-1";
    }
     
 
}
/**************************************************************
	Problem: 1154
	User: wengsihan
	Language: C++
	Result: Accepted
	Time:55 ms
	Memory:2072 kb
****************************************************************/