#include <iostream>
#include <vector>
#include <string>

using namespace std;

int main() {
    cin.sync_with_stdio(false);
    cin.tie(nullptr);

    int N, answer = 0;
    cin >> N;
    for (int i = 1; i <= N; i++) {
        string s;
        cin >> s;
        if (i % 3 == 0 && i % 5 == 0) {
            if (s != "BUMM" && !answer) {
                answer = i;
            }
        }
        else if (i % 5 == 0) {
            if (s != "BAMM" && !answer) {
                answer = i;
            }
        }
        else if (i % 3 == 0) {
            if (s != "BIMM" && !answer) {
                answer = i;
            }
        }
        else if (s != "SZAM" && !answer) {
            answer = i;
        }
    }
    cout << answer << '\n';
}