#include<iostream>
#include<cstdio>

using namespace std;

int main(){
    char ch;
    scanf("%c",&ch);
    double a,sum=0;
    for(int i=0;i<12;i++){
        for(int j=0;j<12;j++){
            cin>>a;
            if(i>j&&i+j<=10) sum+=a;
        }
    }
    if(ch=='S') printf("%.1f\n",sum);
    else if(ch=='M') printf("%.1f\n",sum/30);
    else cout<<"error"<<endl;
    return 0;
}