import math
x = int(input())
y = int(input())
l = int(input())

if x==0:
    if y<0:
        ret = 2
    else:
        ret = 0
    ret += math.ceil(abs(y)/l)
    print(ret)
elif y==0:
    ret = 1
    ret += math.ceil(abs(x)/l)
    print(ret)
else:
    if y<0:
        ret = 2
    else:
        ret = 1
    x = abs(x)
    y = abs(y)
    ret += math.ceil(x/l) + math.ceil(y/l)
    print(ret)