#include <iostream>
#include <cstring>
using namespace std;
void speed()
{
ios_base::sync_with_stdio(false);
cin.tie();
cout.tie();
}
const int MAXN = (int)3e5 + 5;
long long dp[MAXN][2];
long long cnt[MAXN][2];
int a[MAXN], n, k;
void read()
{
cin >> n >> k;
for(int i = 1; i <= n; i++)
cin >> a[i];
}
int check(long long cost)
{
memset(dp, 0, sizeof(dp));
memset(cnt, 0, sizeof(cnt));
dp[1][0] = 0;
cnt[1][0] = 0;
dp[1][1] = a[1] - cost;
cnt[1][1] = 1;
for(int i = 2; i <= n; i++)
{
//cout << i << endl;
if(dp[i - 1][0] >= dp[i - 1][1])
{
dp[i][0] = dp[i - 1][0];
cnt[i][0] = cnt[i - 1][0];
}
else
{
dp[i][0] = dp[i - 1][1];
cnt[i][0] = cnt[i - 1][1];
}
if(dp[i - 1][0] + a[i] - cost > dp[i - 1][1] + a[i])
{
dp[i][1] = dp[i - 1][0] + a[i] - cost;
cnt[i][1] = cnt[i - 1][0] + 1;
}
else
{
dp[i][1] = dp[i - 1][1] + a[i];
cnt[i][1] = cnt[i - 1][1];
}
}
if(max(dp[n][0] + (k * cost), dp[n][1] + (k * cost)) == dp[n][0] + (k * cost))
return cnt[n][0];
else
return cnt[n][1];
}
void binSearch()
{
long long L = 0, R = 1e18, mid;
while(L <= R)
{
mid = (L + R) / 2;
long long ch = check(mid);
if(ch > k)
L = mid + 1;
else
R = mid - 1;
}
if(R == -1)
R = 0;
//cout << L << ' ' << mid << ' ' << R << endl;
cout << max(dp[n][0] + (cnt[n][0] * L), dp[n][1] + (cnt[n][1] * L)) << endl;
}
int main()
{
speed();
read();
binSearch();
return 0;
}
