#include <bits/stdcc+.h>
using namespace std;
int main()
{
	int n ;
	cin >> n;
	int a[105];
	for (int i = 0;i<n;i++)
	{
		cin >> a[i];
	}
	int flag = 0; //flag = 0 表示没找到 
	int k;
	cin >> k;
	for(int i = 0; i < n;i++)
	{
		if (a[i]==k)
		{
			flag = 1;
			cout << i + 1 <<endl;
			break;
		}
	}
	if (flag == 0)
	{
		cout <<-1;
	}
	
	
	
}
/**************************************************************
	Problem: 1154
	User: mariooo
	Language: C++
	Result: Compile Error
****************************************************************/