#include <stdio.h>
int function(int a[],int n, int val)
{
    int i=0,ok=0;
    for(i=0;i<n;i++)
        if(a[i] == val)
        {   ok = 1;
            break;
        }
    if(ok == 1)
        return i;
    else
        return -1;


}
int main()
{
    int n,val;
    scanf("%d",&n);
    int a[200];
    for(int i=0;i<n;i++)
      scanf("%d",&a[i]);
    scanf("%d",&val);
    printf("%d",function(a,n,val));
    return 0;
}