#include <iostream>
#include <string>

using namespace std;

int main() {
    string T;
    cin >> T;

    double M[12][12];
    double data;
    for (int i = 0; i < 12; i++) {
        for (int j = 0; j < 12; j++) {
            cin >> data;
            M[i][j] = data;
        }
    }

    double num;
    double sum;
    for (int i = 0; i < (12/2); i++) {
        for (int j = 0; j < 12; j++) {
            if (i < j && j < (11 - i)) {
                sum += M[i][j];
                num++;
            }
        }
    }

    if (T == "M"){
        sum /= num;
    }

    cout.flags(ios::fixed);
    cout.precision(1);
    cout << sum << endl;

    return 0;
}