import math

X, Y, L = [int(input()) for i in range(3)]

moving = 0

if X > 0 and Y >= 0:
    moving = 1
elif X < 0 and Y >= 0:
    moving = 1
elif X < 0 and Y < 0:
    moving = 2
elif X > 0 and Y < 0:
    moving = 2
elif X == 0 and Y > 0:
    moving = 0
elif X == 0 and Y < 0:
    moving = 2
else:
    moving = 0
    
ans = int(moving + math.ceil(abs(X) / L) + math.ceil(abs(Y) / L))
print(ans)