from math import ceil
X = int(input())
Y = int(input())
L = int(input())
if Y >= 0:
    if X!=0 and Y!=0:
        print(abs(ceil(X/L)) + abs(ceil(Y/L)) + 1)
    else:
        print(abs(ceil(X/L)) + abs(ceil(Y/L)))
else:
    if X!=0 and Y!=0:
        print(abs(ceil(X/L)) + abs(ceil(Y/L)) + 3)
    else:
        print(abs(ceil(X/L)) + abs(ceil(Y/L)) + 2)