import math
# get 3 float number from user 

x = float(input('x : '))
y = float(input('y : '))
z = float(input('z : '))

def calcualte_number(x, y, z):
    avg = (x+y+z) / 3
    return avg

result = math.floor(calcualte_number(x, y, z))
print(result)