#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
#define MP make_pair
#define EPS 0.00001
int n,k;
vector<ll> W;
pair<ll,ll> solve(ll pen) {
vector<vector<pair<ll,ll>>> dp(300005, vector<pair<ll,ll>>(2));
dp[0][0] = {0, 0};
dp[0][1] = {W[0] - pen, 1};
for(int i = 1; i < n; i++) {
dp[i][0] = max(dp[i-1][0], dp[i-1][1]);
dp[i][1] = max(MP(dp[i-1][1].first + W[i], dp[i-1][1].second), MP(dp[i-1][0].first + W[i] - pen, dp[i-1][0].second + 1));
}
return max(dp[n-1][0], dp[n-1][1]);
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> k;
ll lower = 0;
ll upper = 10000000000000;
W.resize(n); for(auto &a : W) cin >> a;
while(lower < upper) {
ll m = (lower+upper+1)/2;
auto K = solve(m);
if(K.second >= k) {
lower = m;
} else {
upper = m-1;
}
}
auto K = solve(lower);
cout << K.first + k*lower;
}
