let n = readLine()!.split(separator: " ").map{Int($0)!}
var a = readLine()!.split(separator: " ").map{Int($0)!}.sorted()
for i in 0...a.count - 1{
    a[i] = a[i] < 0 ? 0 : a[i]
}
a[0] = 0
for i in a[(a.count - n[1])...]{
    a[0] += i
}
print(a[0])