inp = open("input.txt")

n, k = [int(x) for x in inp.readline().split()]

a = []

for i in range(n):
    s = inp.readline() + ' '
    t = ""
    for j in range(len(s)):
        if (s[j] == '-') and (len(t) == 0):
            t += s[j]
        elif (s[j].isdigit()):
            t += s[j]
    a.append(int(t))

a.sort()

open("output.txt", "w").write(str(sum(a[:k])))