#include<stdio.h>
int main()
{
    int n,x,count=0;
    scanf("%d",&n);
    int sequence;
    for(int i=0;i<n;i++)
    {
        scanf("%d",&sequence[i]);
    }
    scanf("%d",&x);
    for(int i=0;i,n;i++)
    {
        if(sequence[i]==x)
        {
            count++;
        }
    }
    if(count==0)
    {
        printf("-1\n");
    }
    else
    {
        printf("%d\n",count);
    }
    return 0;
}