#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef __int128 lll;
typedef long double ld;
typedef pair<ll, ll> pll;
typedef pair<ld, ld> pld;
#define MAX 9223372036854775807LL
#define MIN -9223372036854775807LL
#define INF 0x3f3f3f3f3f3f3f3f
#define fi first
#define se second
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); cout << fixed; cout.precision(10);
#define sp << " "
#define en << "\n"
#define compress(v) sort(v.begin(), v.end()), v.erase(unique(v.begin(), v.end()), v.end())
struct gujo
{
ll V, C;
bool operator < (const gujo &xx) const
{
return C < xx.C;
}
};
ll n, m;
gujo a[200010];
ll ans;
ll last = -1;
int main(void)
{
fastio
cin >> n >> m;
for(ll i = 1 ; i <= n ; i++)
cin >> a[i].V >> a[i].C;
sort(a + 1, a + 1 + n);
for(ll i = m ; i <= n ; i++)
{
ll idx = -1, maxx = -INF;
for(ll j = 1 ; j <= i ; j++)
{
ll sum = a[j].V + 2 * a[j].C + a[i].V - 2 * a[i].C;
vector<ll> gap;
for(ll k = j + 1 ; k < i ; k++)
gap.push_back(a[k].V);
sort(gap.begin(), gap.end());
if((ll)gap.size() < m - 2)
continue;
for(ll k = 0 ; k < m - 2 ; k++)
sum += gap[(ll)gap.size() - 1 - k];
if(maxx < sum)
{
maxx = sum;
idx = j;
}
}
ans = max(ans, maxx);
if(last > idx)
assert(0);
last = idx;
}
cout << ans;
return 0;
}
