/*#pragma GCC optimize("O3")
#pragma GCC optimization("Ofast,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")*/
#include <bits/stdc++.h>
//#include "algotester_generator.h"
/*#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>*/
#define ll long long
#define ll1 long long
#define ull unsigned long long
#define dou long double
#define str string
#define vll vector<ll>
#define vi vector<int>
#define pll pair<ll, ll>
#define vpll vector<pll>
#define vbool vector<bool>
#define vstr vector<str>
#define vvll vector<vll>
#define pb push_back
#define pf push_front
#define endl "\n"
#define fr first
#define se second
// #define sortcmp(a) sort(a.begin(), a.end(), cmp)
#define sort(a) sort(a.begin(), a.end())
#define reverse(a) reverse(a.begin(), a.end())
#define speed ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define INF 1000000000000000000
#define ordered_set tree<ll, null_type, less_equal<ll>, rb_tree_tag, tree_order_statistics_node_update>
using namespace std;
//using namespace __gnu_pbds;
mt19937 rng(time(0));
ll randll(ll l, ll r){
return uniform_int_distribution<ll>(l, r)(rng);
}
int main(){
speed;
ll n, m;
cin >> n >> m;
vll a(n);
for(int i =0 ; i < n; i ++){
cin >> a[i];
}
vll v;
ll k = a[0];
for(int i = 1; i < n; i ++){
if((a[i] < 0) != (a[i-1] < 0)){
v.pb(k);
k = a[i];
}
else k += a[i];
}
v.pb(k);
if(v.back() < 0) v.pop_back();
vll v1, v2;
k = 0;
for(int i = 0; i < v.size(); i ++){
if(k+v[i] <= 0){
v1.pb(k);
k = 0;
}
else{
k += v[i];
if(v[i] < 0) v2.pb(v[i]);
}
}
v1.pb(k);
sort(v1);
sort(v2);
/*for(int i : v1){
cout << i << ' ';
}*/
//cout << endl;
ll res = 0;
if(v1.size() >= m){
reverse(v1);
for(int i = 0; i < m; i ++){
res += v1[i];
}
cout << res << endl;
}
else{
reverse(v1);
for(int i = 0; i < v1.size(); i ++){
res += v1[i];
}
for(int i = 0; i < min(m-(ll)v1.size(), (ll)v2.size()); i ++){
res -= v2[i];
}
cout << res << endl;
}
//cout << 1 << endl;
}
