import math

x, y, r = list(map(int, input().split()))

if x < 0:
    x = -x
if y < 0:
    y = -y

l1_dist = x + y + math.sqrt(2) * r

if l1_dist > int(l1_dist):
    print(int(l1_dist) + 1)
else:
    print(int(l1_dist))