#include<cstdio>

int main() {
    char t;
    scanf("%c",&t);

    double q[12][12]; // 初始化后全部读入
    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;
}