You are given three integers A, B and C. Find the minimum number of operations required to make A, B and C all equal by repeatedly performing the following two kinds of operations in any order:    * Choose two among A, B and C, then increase both by 1.   * Choose one among A, B and C, then increase it by 2.  It can be proved that we can always make A, B and C all equal by repeatedly performing these operations.
ABC = list(map(int,input().split()))

if (max(ABC) + ABC[0] + ABC[1] + ABC[2]) % 2 == 0:
    print((max(ABC) * 3 - ABC[0] - ABC[1] - ABC[2]) / 2)
else:
    print(((max(ABC) + 1) * 3 - ABC[0] - ABC[1] - ABC[2]) / 2)
import math

ABC = list(map(int,input().split()))

score = 0

if (max(ABC) + ABC[0] + ABC[1] + ABC[2]) % 2 == 0:
    score = (max(ABC) * 3 - ABC[0] - ABC[1] - ABC[2])
else:
    score = ((max(ABC) + 1) * 3 - ABC[0] - ABC[1] - ABC[2])

print(math.floor(score/2))