#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll mn = -(1ll<<60);
void solve(){
int n, k; cin >> n >> k;
vector<ll> v(n);
for(auto &x : v)cin >> x;
ll l = 0, r = (1ll<<42), bes = 0;
while(l<=r){
ll m = (l+r)>>1;
vector<vector<pair<ll,ll>>> dp(n,vector<pair<ll,ll>>(2));
dp[0][0] = {0,0};
dp[0][1] = {-m+v[0],0};
for(int i = 1; i < n; ++i){
dp[i][0] = max(dp[i-1][0],{dp[i-1][1].first,dp[i-1][1].second+1});
dp[i][1] = max(dp[i-1][1],{dp[i-1][0].first-m,dp[i-1][0].second});
dp[i][1].first+=v[i];
}
pair<ll,ll> b = max(dp[n-1][0], dp[n-1][1]);
if(b.second >= m){
bes = b.first + m*k;
l = m+1;
}
else{
r = m-1;
}
}
cout << bes << '\n';
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
solve();
}
