#include <stdio.h>

int main() {
    int n;
    while ((scanf("%d", &n)) != EOF) {
        int m = n;
        int Arr[n];
        int i = 0;
        Arr[n] = -1;
        while (n--) {
            scanf("%d", &Arr[i++]);
        }
        int number;
        scanf("%d", &number);
        int j;
        for (j = 0; j < m; j++) {
            if (Arr[j] == number) {
                printf("%d\n", j);
                break;
            }
        }
        if (j == m) {
            printf("-1\n");
        }
    }
    return 0;
}