x = int(input())
y = int(input())
l = int(input())

turn = 1
if x == 0 and y == 0:
    print(0)
elif x == 0 and y > 0:
    if y % l == 0:
        print(y // l)
    else:
        print(y // l + 1)
elif y >= 0:
    if abs(x) % l == 0 and abs(y) % l == 0:
        print(abs(x) // l + abs(y) // l + turn)
    elif abs(x) % l == 0 or abs(y) % l == 0:
        print(abs(x) // l + abs(y) // l + 1 + turn)
    else:
        print(abs(x) // l + abs(y) // l + 2 + turn)
else:
    if abs(x) % l == 0 and abs(y) % l == 0:
        print(abs(x) // l + abs(y) // l + turn * 2)
    elif abs(x) % l == 0 or abs(y) % l == 0:
        print(abs(x) // l + abs(y) // l + 1 + turn * 2)
    else:
        print(abs(x) // l + abs(y) // l + 2 + turn * 2)