import math
import sys
def S(): return sys.stdin.readline().rstrip()
def I(): return int(sys.stdin.readline().rstrip())
def MI(): return map(int, sys.stdin.readline().rstrip().split())
def LI(): return list(map(int, sys.stdin.readline().rstrip().split()))
def LS(): return list(sys.stdin.readline().rstrip().split())

x, y, r = MI()

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

print(math.ceil(x+y+2*(r/2**0.5)))