//#include "holiday.h"
#include <bits/stdc++.h>
#define pb push_back
#define task "sequence"
#define pll pair<ll, ll>
#define pii pair<vector<ll>, ll>
#define fi first
#define se second
using ll = int;
const long long mod = 1e16+7;
const ll mod1 = 1e9+1;
const ll N = 2e5+5;
const int base = 350;
using ull = unsigned long long;
using namespace std;
ll n, m, t, k, T, u, v, a[N], c[N], d[N], b[N], cnt[N*4], s;
long long ans, tong, sum[N*4];
vector<ll> adj[N], kq;
vector<pll> l, r;
pll p[N];
void update(ll id, ll l, ll r, ll pos)
{
if(l == r)
{
if(cnt[id] == 0)
{
cnt[id] = 1;
sum[id] = p[c[l]].se;
}
else
{
cnt[id] = 0;
sum[id] = 0;
}
return;
}
ll mid = (l + r) / 2;
if(mid >= pos)update(id*2, l, mid, pos);
else update(id*2+1, mid+1, r, pos);
sum[id] = sum[id*2] + sum[id*2+1];
cnt[id] = cnt[id*2] + cnt[id*2+1];
}
long long get(ll id, ll l, ll r, ll k)
{
//if(t == 1)cout << l <<" "<<r<<" "<<k<<" "<<sum[id]<<" " << cnt[id] <<" "<<cnt[id*2]<< '\n';
if(cnt[id] <= k)return sum[id];
if(k == 0 || l == r)return 0;
if(k < 0)return -mod;
ll mid = (l + r) / 2;
if(cnt[id*2] >= k)return get(id*2, l, mid, k);
else return sum[id*2] + get(id*2+1, mid+1, r, k-cnt[id*2]);
}
void add(ll cl, ll cr)
{
while(u < cl)
{
update(1, 1, n, b[u]);
++u;
}
while(u > cl)
{
--u;
update(1, 1, n, b[u]);
}
while(v < cr)
{
++v;
update(1, 1, n, b[v]);
}
while(v > cr)
{
update(1, 1, n, b[v]);
--v;
}
}
void cal(ll l, ll r, ll opl, ll opr)
{
if(l > r)return;
ll mid = (l + r) / 2;
ll best = opl;
long long val = -mod;
for(int i = opl; i <= min(mid-m+1, opr); i ++)
{
add(i, mid);
if(mid - i + 1 >= m)
{
update(1, 1, n, b[i]);
update(1, 1, n, b[mid]);
tong = get(1, 1, n, m-2);
//cout << i <<" "<<mid<<" "<<tong<<'\n';
tong += p[i].se + p[mid].se - 2*(p[mid].fi - p[i].fi);
update(1, 1, n, b[i]);
update(1, 1, n, b[mid]);
}
else tong = -mod;
if(tong > val)
{
val = tong;
best = i;
}
//cout << "ok" <<" ";
}
//cout << l <<" "<<r<<" "<<mid<<" "<<opl<< " "<<opr<<" "<<val<<endl;
//cout << l <<" "<< r << " " << mid << endl;;
ans = max(ans, val);
cal(l, mid-1, opl, best);
cal(mid+1, r, best, opr);
}
bool cmp(const ll& x, const ll& y)
{
return p[x].se > p[y].se;
}
void sol()
{
cin >> n >> m;
for(int i = 1; i <= n; i ++)
{
cin >> p[i].se >> p[i].fi;
c[i] = i;
}
ans = -mod;
u = 2, v = 1;
sort(p+1, p+1+n);
sort(c+1, c+1+n, cmp);
for(int i = 1; i <= n; i ++)b[c[i]] = i;
//for(int i = 1; i <= n; i ++)cout << b[i] <<" " ;
cal(1, n, 1, n);
cout << ans;
}
int main()
{
if(fopen(task".in", "r")){
freopen(task".in", "r", stdin);
freopen(task".out", "w", stdout);
}
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int ntest;
ntest = 1;
//cin >> ntest;
//cout << (1<<30) << '\n';
while(ntest -- > 0)
sol();
}
/*
5 7 3
10 2 20 30 1
*/
