#include <bits/stdc++.h>
#define pb push_back
#define ppb pop_back
#define fi first
#define se second
#define mid ((x + y) / 2)
#define left (ind * 2)
#define right (ind * 2 + 1)
#define mp make_pair
#define timer ((double)clock() / CLOCKS_PER_SEC)
#define endl "\n"
#define spc " "
#define d1(x) cerr<<#x<<":"<<x<<endl
#define d2(x, y) cerr<<#x<<":"<<x<<" "<<#y<<":"<<y<<endl
#define d3(x, y, z) cerr<<#x<<":"<<x<<" "<<#y<<":"<<y<<" "<<#z<<":"<<z<<endl
#define fast_io() ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0)
using namespace std;
typedef long long int lli;
typedef pair<lli, lli> ii;
typedef pair<ii, int> iii;
typedef pair<double, double> dd;
const int N = (int)(1e2 + 5);
const int LOG = (int)(20);
const lli inf = (lli)(1e15);
lli n, m, ans, dp[N][N][N];
ii p[N];
lli f(int x, int y, int z) {
if(z < 0)
return -inf;
if(x == y + 1) {
if(z == 0)
return 0;
else
return -inf;
}
if(dp[x][y][z] != -1)
return dp[x][y][z];
return dp[x][y][z] = max(f(x + 1, y, z), f(x + 1, y, z - 1) + p[x].se);
}
int main() {
fast_io();
// freopen("inp.in", "r", stdin);
memset(dp, -1, sizeof dp);
cin >> n >> m;
for(int i = 1; i <= n; i++)
cin >> p[i].se >> p[i].fi;
sort(p + 1, p + n + 1);
for(int i = 1; i <= n; i++)
for(int j = i + m - 1; j <= n; j++)
ans = max(ans, f(i + 1, j - 1, m - 2) + p[i].se + p[j].se - 2 * (p[j].fi - p[i].fi));
cout << ans;
}
