import sys

sys.setrecursionlimit(10 ** 6)

def main():
    x = int(input())
    y = int(input())
    l = int(input())
    if y < 0:
        ans = 2
    elif x == 0:
        ans = 0
    else:
        ans = 1
    ans += (abs(x) + l - 1) // l + (abs(y) + l - 1) // l
    print(ans)

main()