import sequtils,strutils,math
var
    x = stdin.readline.parseInt
    y = stdin.readline.parseInt
    L = stdin.readline.parseInt
    cnt = 0

if y >= 0 and x == 0:
    cnt = 0
elif y >= 0:
    cnt = 1
else:
    cnt = 2
    
cnt += ceil(abs(x / L)).int
cnt += ceil(abs(y / L)).int

echo cnt