#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;
	return 0;
}
/**************************************************************
	Problem: 1154
	User: zzz
	Language: C++
	Result: Accepted
	Time:28 ms
	Memory:2072 kb
****************************************************************/