mode = input()
desk = [list(map(float,input().split())) for i in range(12)] #生成数组
num = 0#计算有多少个块
summ = 0#计算像素总和
for i in range(5):
for j in range(i+1,12-i-1):
summ += desk[i][j]
num += 1
if mode == 'S':
print(f'{summ:.1f}')
else:
print(f'{summ / num:1f}')