#include <bits/stdc++.h>
using namespace std;
int main(){
    int m,a[100],n;
    cin>>m;
    for(int i=0;i<n;i++){
    	cin>>a[i];
    }
    cin>>n;
    for(int i=0;i<n;i++){
    	if(a[i]==n){
    		cout<<i;
    		return 0;
    	}
    }
    cout<<"-1";
}
/**************************************************************
	Problem: 1154
	User: wangyiyang
	Language: C++
	Result: Wrong Answer
****************************************************************/