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

cmd = 0
cmd += ceil(abs(Y) / L) + ceil(abs(X) / L)
if Y > 0:
    if X != 0:
        cmd += 1
elif Y == 0:
    if X != 0:
        cmd += 1
else:
    cmd += 2
print(cmd)