using namespace std;
int main() {
int n, m;
while (cin >> n) {
int a[n];
for (int i = 0; i < n; ++i) {
cin >> a[i];
}
cin >> m;
int num = -1;
for (int i = 0; i < n; ++i) {
if (a[i] == m) {
num = i;
break;
}
}
if (num != -1) {
cout << num << endl;
} else {
cout << "No" << endl;
}
}
return 0;
}