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