#include <any>
#include <bits/stdc++.h>
#include <utility>
#include <vector>
using namespace std;
#ifndef LOCAL
#define cerr if(false) cerr
#endif
#define out( x ) #x << " = " << x << " "
#define endl "\n"
template<class T, class T2> inline bool chkmax(T &x, const T2 &y) { return x < y ? x = y, 1 : 0; }
template<class T, class T2> inline bool chkmin(T &x, const T2 &y) { return x > y ? x = y, 1 : 0; }
typedef long long ll;
#define int ll
const ll mod = 3e14 +7;
const int MAX_N = 3e5 + 42;
std::pair< ll, int > dp[MAX_N][2];
ll a[MAX_N];
int n, k;
std::pair< ll, int > aliens( ll x ){
dp[0][1] = make_pair( a[0] - x, 1 );
dp[0][0] = std::make_pair( 0, 0 );
for (int i=1;i<n;i++) {
std::pair< ll, int > A;
A.first = dp[i-1][1].first + a[i];
A.second = dp[i-1][1].second;
std::pair< ll, int > B;
B.first = dp[i-1][0].first + a[i] - x;
B.second = dp[i-1][0].second + 1;
dp[i][1] = std::max( A, B );
dp[i][0] = max( dp[i-1][0], dp[i-1][1]);
}
return max(dp[n-1][0],dp[n-1][1]);
}
signed main(){
#ifndef LOCAL
std::ios_base::sync_with_stdio( false ); std::cin.tie( NULL ); std::cout.tie( NULL );
#endif
std::cin >> n >> k;
for( int i=0 ; i < n ; i++ ) std::cin >> a[i];
ll l = 0, r = mod;
while( l != r-1 ) {
ll mid = ( l + r ) >> 1;
if (aliens(mid).second >= k) l = mid;
else r = mid;
}
cout << aliens(l).first + l * k << "\n";
return 0;
}
