X = int(input())
Y = int(input())
L = int(input())
Ans = 0
Ans = int(abs(Y)/L) + int(abs(X)/L)
if Y%L != 0:
    Ans += 1
if X%L != 0:
    Ans += 1
if X != 0 and Y < 0:
    Ans += 2
else:
    Ans += 1
print(Ans)