#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;

int main()
{
    double a[12][12];
    char t;
    cin >> t;
    for (int i = 0; i < 12; i++)
        for (int j = 0; j < 12; j++) cin >> a[i][j];

    double sum = 0, cnt = 0;
    for (int i = 11; i > 6; i--)
    {
        for (int j = 1 + abs(11 - i); j <= i - 1; j++)
        {
            sum += a[i][j];
            cnt ++;
        }
    }
    if (t == 'S') printf("%.1lf", sum);
    else printf("%.1lf", sum / cnt);

    return 0;
}