c = int(input())
sm = input()
m = []
s = 0
for i in range(12):
    m.append(list(map(float,input().split())))
for i in range(12):
    s += m[i][c]


if sm == 'S':
    print("%.1lf"%s)
elif sm == 'M':
    print("%.1lf"%(s/12))