#include <iostream>
#include <cstdio>
using namespace std;
int main() {
double m[12][12], sum = 0;
int k = 0;
char c;
cin >> c;
for (int i = 0; i < 12; ++i) {
for (int j = 0; j < 12; ++j) {
cin >> m[i][j];
}
}
for (int i = 7; i < 12; ++i) {
for (int j = 12 - i; j < i; ++j) {
sum += m[i][j];
k++;
}
}
if (c == 'S'){
printf("%.1lf\n", sum);
} else {
printf("%.1lf\n", sum / k);
}
return 0;
}