#include <bits/stdc++.h>
using namespace std;
double a, ans, cnt;
int main() {
    int l;
    char t;
    cin >> l >> t;
    for (int i = 0; i < 12; i ++ ) {
        for (int j = 0; j < 12; j ++ ) {
            cin >> a;
            if (j == l) ans += a, cnt ++;
        }
    }
    if(t == 'M') ans /= cnt;
    printf("%.1lf", ans);
}