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