#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n,cnt=0;
    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<<" ";
            break;
        }
        else
        {
            cnt=1;
        }
    }
    if(cnt=1)
    {
        cout<<-1;
    }
    return 0;
}
/**************************************************************
	Problem: 1154
	User: wuyichen
	Language: C++
	Result: Wrong Answer
****************************************************************/