// bimm,bamm,bumm.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#include <iostream>
#include <cstring>
#include <vector>

using namespace std;

int n, i, j;
char x[10], s1 = 'BIMM', s2 = 'BAMM', s3 = 'BUMM', s4 = 'SZAM';

int main()
{
    cin >> n;
    cin.getline(x, 10);
    for (i = 1; i <= n; ++i)
    {
        cin.getline(x, 10);
        if (i % 3 == 0 && i % 5 != 0)
        {
            if (strcmp(x, "BIMM"))
            {
                cout << i;
                break;
            }
        }
        else if (i % 3 != 0 && i % 5 == 0)
        {
            if (strcmp(x, "BAMM"))
            {
                cout << i;
                break;
            }
        }
        else if (i % 3 == 0 && i % 5 == 0)
        {
            if (strcmp(x, "BUMM"))
            {
                cout << i;
                break;
            }
        }
        else
        {
            if (strcmp(x, "SZAM"))
            {
                cout << i;
                break;
            }
        }
    }
    return 0;
}
/*
4
SZAM
SZAM
BIMM
BIMM

5
SZAM
SZAM
BAMM
SZAM
SZAM
*/
// Run program: Ctrl + F5 or Debug > Start Without Debugging menu
// Debug program: F5 or Debug > Start Debugging menu

// Tips for Getting Started: 
//   1. Use the Solution Explorer window to add/manage files
//   2. Use the Team Explorer window to connect to source control
//   3. Use the Output window to see build output and other messages
//   4. Use the Error List window to view errors
//   5. Go to Project > Add New Item to create new code files, or Project > Add Existing Item to add existing code files to the project
//   6. In the future, to open this project again, go to File > Open > Project and select the .sln file