#include <iostream>
#include <iomanip>
#include <cmath>

using namespace std;

int main(){
	int a[100],n,s;
	bool f=false;
	cin>>n;
	for(int i=0;i<n;i++){
		cin>>a[i];
	}
	cin>>s;
	for(int i=0;i<n;i++){
		if(a[i]==s){
			cout<<i+1<<endl;
			f=true;
			break;
		}
	}
	
	if(f==false){
		cout<<"-1"<<endl;
	}
}
/**************************************************************
	Problem: 1154
	User: admin
	Language: C++
	Result: Accepted
	Time:20 ms
	Memory:2072 kb
****************************************************************/