#include <cstdio>
using namespace std;
int main()
{
    char t;
    scanf("%c", &t);
    double q[12][12];
    for (int i = 0; i < 12; i ++ )
        for (int j = 0; j < 12; j ++ )
            scanf("%lf", &q[i][j]);
    double s = 0, c = 0;
    for (int i = 1; i <= 5; i ++ )
        for (int j = 0; j <= i - 1; j ++ )
        {
            s += q[i][j];
            c += 1;
        }
    for (int i = 6; i <= 10; i ++ )
        for (int j = 0; j <= 10 - i; j ++ )
        {
            s += q[i][j];
            c += 1;
        }
    if (t == 'S') printf("%.1lf\n", s);
    else printf("%.1lf\n", s / c);
    return 0;
}