import sys
import itertools

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

    ans = 0
    if Y < 0:
        ans += 2
    elif X != 0:
        ans += 1
    ans += (-(-abs(X) // L)) + (-(-abs(Y) // L))

    return ans


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


if __name__ == '__main__':
    main()