#include <bits/stdc++.h> using namespace std; using ll = long long; #define vi vector<long long> #define all(x) x.begin(), x.end() #define endl "\n" void solution(); int main(){ ios::sync_with_stdio(false); cin.tie(nullptr); solution(); return 0; } const int N = 3e5+10; ll a[N]; void solution() { ll n, k; cin >> n >> k; for (int i = 1; i <= n; i++) cin >> a[i]; ll sum = accumulate(a+1, a+1+n, 0ll); int id = 0; ll s1 = 0; for (int i = 1; i <= n; i++) { s1 += a[i]; if (a[i] < 0) {id = i; break;} } if (k > 1) { cout << sum << endl; } else { cout << max({sum, s1, sum-a[id]-s1}) << endl; } }