#include <iostream>
#include <vector>
using namespace std;

int main()
{
	int n;
	cin >> n;

	vector<string>list(n);

	for (int i = 0; i < n; i++)
	{
		cin >> list[i];
	}

	int i = 0;
	
	while (i < n && ((((i + 1) % 3 == 0 && (i + 1) % 5 == 0) && list[i] == "BUMM" || ((i + 1) % 3 == 0 && list[i] == "BIMM")) || (((i + 1) % 5 == 0 && list[i] == "BAMM") || list[i] == "SZAM"))) {
		i++;
	}

	if (i == n)
		cout << 0;
	else
		cout << i + 1;
}

//i % 3 == 0 && i % 5 == 0) && list[i] == "BUMM"
//i % 3 == 0 && list[i] == "BIMM"
//i % 5 == 0 && list[i] == "BAMM"
//list[i] == "SZAM"