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

int main()
{int i,q=0,t=1,n; char a[1001][10];
    cin>>n;
    for(i=0;i<n;i++){
        cin.get();
        cin.get(a[i],10);
    }
    for(i=0;i<n;i++){
        if((i+1)%3!=0 && t==1 && (i+1)%5!=0 && strcmp(a[i],"SZAM")!=0){t=0;q=i+1;}
        if((i+1)%3==0 && t==1 && (i+1)%5!=0 && strcmp(a[i],"BIMM")!=0){t=0;q=i+1;}
        if((i+1)%3!=0 && t==1 && (i+1)%5==0 && strcmp(a[i],"BAMM")!=0){t=0;q=i+1;}
        if((i+1)%3==0 && t==1 && (i+1)%5==0 && strcmp(a[i],"BUMM")!=0){t=0;q=i+1;}
    }cout<<q;
    return 0;
}