#include <cstdio>

int main()
{
    char t;
    scanf("%c", &t);
    double a[12][12];

    for (int i = 0; i < 12; i++)
    {
        for (int j = 0; j < 12; j++) scanf("%lf", &a[i][j]);
    }

    int c = 0;
    double sum = 0;

    for (int i = 1; i <= 5; i++)
    {
        for (int j = 0; j <= i - 1; j++)
        {
            sum += a[i][j];
            c += 1;
        }
    }

    for (int i = 6; i < 11; i++)
    {
        for (int j = 0; j <= 10 - i; j++)
        {
            sum += a[i][j];
            c += 1;
        }
    }


    if (t == 'S') printf("%.1lf", sum);
    else printf("%.1lf", sum / c);

    return 0;
}