#include <cstdio>
int main() {
char t;
double a[12][12];
scanf("%c", &t);
for (int i = 0; i < 12; i ++ )
for (int j = 0; j < 12; j ++ )
scanf("%lf", &a[i][j]);
int cnt = 0;
double s = 0;
for (int i = 0; i < 5; i ++ )
for (int j = i + 1; j <= 10 - i; j ++ ) {
cnt ++ ;
s += a[i][j];
}
if (t == 'S') printf("%.1lf\n", s);
else printf("%.1lf\n", s / cnt);
return 0;
}