oper = input()

matriz = [ [float(input()) for _ in range(12)] for _ in range(12)]

soma = sum( sum(matriz[l][0:l]) for l in range(1, 12) )
cont = (1+11)*11/2

if oper = 'S':
    print(f"{soma:.1f}")
else:
    media = soma / cont
    print(f"{media:.1f}")