Python3 代码

s = input()

sum = 0
count = 0
for i in range (12):
    n = list(map(float, input().split()))
    for j in range (i+1, 12):
        sum += n[j]
        count += 1

if s == "S":
    print (f'{sum:.1f}')
if s == "M":
    print (f'{sum/count:.1f}')