import java.io.;
import java.util.;
public class Main{
public static void main(String args[]) throws Exception {
var M = new double[12][12];
Scanner cin = new Scanner(System.in);
var C = cin.next().charAt(0);
for(int i = 0; i < 12; i++){
for(int j = 0; j < 12; j++){
M[i][j] = cin.nextDouble();
}
}
int c = 0;
double s = 0;
for(int i = 1; i <= 5; i++){
for(int j = 0; j <= i - 1; j++){
c++;
s += M[i][j];
}
}
for(int i = 6; i <= 10; i++){
for(int j = 0; j <= 10 - i; j++){
c++;
s += M[i][j];
}
}
if(C == 'S'){ //Java识别单个字符
System.out.printf("%.1f\n", s);
}
else{
System.out.printf("%.1f\n", s/c);
}
}
}