import java.io.;
import java.util.;
public class Main{
public static void main(String arges[]) throws Exception {
var M = new double[12][12];
Scanner cin = new Scanner(System.in);
var C = cin.next().charAt(0); //(choice)在Java中读入单个字符的方法
for(int i = 0; i < 12; i++){
for(int j = 0; j < 12; j++){
M[i][j] = cin.nextDouble();
}
}
int c = 0; //(count)个数用c表示
double s = 0; //(sum)总和用s表示
for(int i = 0; i < 12; 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);
}
}
}