//土尔逊Torson 编写于2023/4/14
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <cstdio>

using namespace std;

int main() {
	int n;
	int arr[201];
	while (scanf("%d", &n) != EOF) {
		for (int i = 0; i < n; ++i) {
			scanf("%d", &arr[i]);
		}
		int x;
		scanf("%d", &x);
		int pos = -1;
		for (int i = 0; i < n; ++i) {
			if (x == arr[i]) {
				pos = i;
				break;
			}
		}
		printf("%d\n", pos);
	}
	system("pause");
	return EXIT_SUCCESS;
}
// 64 位输出请用 printf("%lld")