// Source: https://usaco.guide/general/io
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define eb emplace_back // faster than push_back xD
// pbds UwU
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define oset tree<ll, null_type,less<ll>, rb_tree_tag,tree_order_statistics_node_update> // use pair for ms
// my io library :D
#define m1(x) template<class T, class... U> void x(T&& a, U&&... b)
#define m2(x) (ll[]){(x forward<U>(b),0)...}
m1(pr){cout << forward<T>(a); m2(cout << " " <<); cout << "\n";}
m1(re){cin >> forward<T>(a); m2(cin >>);}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
ll n, k; re(n, k);
vector<ll> a(n);
for (ll i{}; i < n; i++) re(a[i]);
ll sum = accumulate(a.begin(), a.end(), 0LL);
vector<ll> prefsum(n+1, 0), suffsum(n+1, 0);
for (ll i{}; i < n; i++){
prefsum[i+1] = prefsum[i] + a[i];
}
for (ll i=n-1; i >= 0; i--){
suffsum[i] = suffsum[i+1] + a[i];
}
for (ll i{}; i < n; i++){
if (a[i] < 0){
pr(prefsum[i] + suffsum[i+1]); break;
}
if (i == n-1) pr(sum);
}
}
