#include <bits/stdc++.h>
using namespace std;
int main()
{
	int n,i,k,m,a[101];
	bool t=0;
cin>>m;
	for(i=1;i<=m;i++)
	{
		cin>>a[i];
	}
	cin>>n;
	for(i=1;i<=m;i++)
	{
		if(a[i]==n) {
		t=1; k=i; break;
		}	
	
	}
	if(t==0) cout<<-1;
	else cout<<k;
	
	return 0;
}

/**************************************************************
	Problem: 1154
	User: 21A
	Language: C++
	Result: Accepted
	Time:14 ms
	Memory:2072 kb
****************************************************************/