import sys
import itertools

def resolve(in_):
    X = int(next(in_))
    Y = int(next(in_))
    L = int(next(in_))

    ans = 1
    if X == 0 or Y == 0:
        ans -= 1
    ans += -(-abs(X) // L) + -(-abs(Y) // L)

    return ans


def main():
    ans = resolve(sys.stdin)
    print(ans)


if __name__ == '__main__':
    main()