#!/usr/bin/env python3


def optimize(n, k, bs):
    cs = sorted((b for b in bs if b >= 0), reverse=True)
    return sum(cs[:k])


def main():
    n, k = (int(z) for z in input().split())
    bs = [int(b) for b in input().split()]
    res = optimize(n, k, bs)
    print(res)


if __name__ == "__main__":
    main()