#include <iostream>

using namespace std;

int f(int i)
{
    cout<<i;
    return 0;
}

int main()
{
    int n;
    cin>>n;
    for(int i=1;i<=n;++i)
    {
        string s;
        cin>>s;
        if(i%3==0 and i%5==0 and s!="BUMM") return f(i);
        else if(i%3==0 and s!="BIMM") return f(i);
        else if(i%5==0 and s!="BAMM") return f(i);
        else if(s!="SZAM") return f(i);
    }

    return 0;
}