#include <iostream>

using namespace std;

int main()
{
    const int ARRAY_SIZE = 20;
    int arr[ARRAY_SIZE] = {0};
    int size;
    while (cin >> size) {
        for (int i = 0; i < size; i++) {
            cin >> arr[i];
        }
        int find;
        cin >> find;
        bool flag = false;
        for (int i = 0; i < size; i++) {
            if (arr[i] == find) {
                flag = true;
                cout << i << endl;
                break;
            }
        }
        if (!flag) {
            cout << "No" << endl;
        }
    }

    return 0;
}