import math
X = int(input())
Y = int(input())
L = int(input())

cnt = 0

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

print(cnt)