import math
def s(x,y,z,a,b,c):
    if a**2+b**2==0:return False
    if c>0:
        if a*x+b*y+c<=0:return False
    else:
        if a*x+b*y+c>=0:return False
    return abs(a*x+b*y+c)/math.sqrt(a**2+b**2)>z

x,y,z=[int(i) for i in input().split(" ")]
n=1
while True:
    if s(x,y,z,1,1,n)*s(x,y,z,1,-1,n)*s(x,y,z,1,1,-n)*s(x,y,z,1,-1,-n):break
    n+=1
print(n)