#include <iostream>
#include <cstdio>

using namespace std;

int main()
{
    char t;
    cin >> t;

    double x[13][13];
    for(int i = 1; i <=12; i++)
        for (int j = 1; j <= 12; j++)
            cin >> x[i][j];

    int cnt = 0;
    double sum = 0;
    for(int i = 1; i <= 5; i++)
        for (int j = i + 1; j <= 12 - i; j++)
        {
            sum += x[i][j];
            cnt++;
        }

   // cout << cnt << endl;

    if(t == 'M') sum /= cnt;
    printf("%.1lf", sum);

    return 0;
}