#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,cnt=0; //cnt= 0表示没找到
    cin>>n;
    int a[105];
    for(int i=0;i<n;i++)
    {
        cin>>a[i];
    }
    int k;
    cin>>k;
    for(int i=0;i<n;i++)
    {
        if(a[i] == k)
        {
            cout << i + 1 <<endl;
            cnt = 1;
            break;
        }
    }
    if(cnt==0)
    {
        cout<<"-1";
    }
    return 0;
}
/**************************************************************
	Problem: 1154
	User: wuyichen
	Language: C++
	Result: Accepted
	Time:84 ms
	Memory:2072 kb
****************************************************************/