#include<cstdio>

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

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

    double sum = 0.0;
    int c = 0;
    for(int j = 7; j < 12; ++j)
        for(int i = 12 - j; i < j; ++i){
            sum += m[i][j];
            ++ c;
        }

    if(s == 'S')
        printf("%.1lf", sum);
    else
        printf("%.1lf", sum / c);

    return 0;
}