X = int(raw_input())
Y = int(raw_input())
L = int(raw_input())

count = 0
if Y < 0:
    count += 2
elif X < 0:
    count += 1
elif X > 0:
    count += 1
else:
    count += 0

if Y < 0:
    Y = abs(Y)

if X < 0:
    X = abs(X)

count += Y // L
count += (Y % L) > 0

count += X // L
count += (X % L) > 0

print count