#include "stdio.h"
#include "algorithm"
using namespace std;

int main(){
    int n;
    int num[200];
    int x,flag=-1;
    while (scanf("%d",&n)!=EOF){
        flag=-1;
        for (int i = 0; i < n; ++i) {
            scanf("%d",&num[i]);
        }
        scanf("%d",&x);
        for (int i = 0; i < n; ++i) {
            if(num[i]==x){
                flag=i;
                break;
            }
        }
        printf("%d\n",flag);
    }
}