#include <cstdio>

int main() {
    double M[12][12];
    char c;
    double res = 0;
    scanf("%c", &c);
    int cnt = 0;
    for (int i = 0; i < 12; i++) {
        for (int j = 0; j < 12; j++) {
            scanf("%lf", &M[i][j]);
            if (i < j && i + j >= 12) res += M[i][j], cnt++;
        }
    }
    if (c == 'M') res /= cnt;
    printf("%.1lf", res);
    return 0;
}