#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n,a,t=-1;
	cin>>n;
	int m[105];
	for(int i=0;i<n;i++) cin>>m[i];
	cin>>a;
	for(int i=0;i<n;i++)
	{
		if(m[i]==a)
		{
			t=i+1;
			break;
		}
	}
	cout<<t;
	return 0;
}


/**************************************************************
	Problem: 1154
	User: lzc
	Language: C++
	Result: Accepted
	Time:22 ms
	Memory:2072 kb
****************************************************************/