#include<bits/stdc++.h>
#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
#define pb push_back
#define pii pair<int, int>
#define pll pair<ll, ll>
#define st first
#define nd second
#define ordered_set tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>
#define debug false
const int MAXN = 200 * 1000 + 17;
const int MAXLOG = 20;
const ll INF = ll(-1000 * 1000 * 1000) * ll(1000 * 1000 * 1000);
pii a[MAXN];
pair<int, ll> pst[4 * MAXN * MAXLOG];
int l[4 * MAXN * MAXLOG];
int r[4 * MAXN * MAXLOG];
int korzen[MAXN];
ll wyn[MAXN];
vector<int> vec;
int cnt = 0;
int M;
int f (int x) {
return lower_bound(vec.begin(), vec.end(), x) - vec.begin();
}
void buduj (int p, int k, int i) {
cnt = max(cnt, i);
if (p == k) {
return;
}
int sr = (p + k)/ 2;
l[i] = i * 2;
r[i] = i * 2 + 1;
buduj(p, sr, i * 2);
buduj(sr + 1, k, i * 2 + 1);
}
void lacz (int i) {
pst[i].st = pst[l[i]].st + pst[r[i]].st;
pst[i].nd = pst[l[i]].nd + pst[r[i]].nd;
}
void aktualizuj (int p, int k, int ind, ll w, int i, int i2) {
pst[i] = pst[i2];
if (p == k) {
pst[i].st ++;
pst[i].nd += w;
return;
}
int sr = (p + k)/ 2;
if (ind <= sr) {
r[i] = r[i2];
cnt ++;
l[i] = cnt;
aktualizuj(p, sr, ind, w, cnt, l[i2]);
} else {
l[i] = l[i2];
cnt ++;
r[i] = cnt;
aktualizuj(sr + 1, k, ind, w, cnt, r[i2]);
}
lacz(i);
}
ll odczytaj (int p, int k, int m, int i, int i2) {
if ((pst[i].st - pst[i2].st) == m) {
return (pst[i].nd - pst[i2].nd);
}
if (p == k) {
return ll(m) * ll(vec[p]);
}
int sr = (p + k)/ 2;
if ((pst[r[i]].st - pst[r[i2]].st) >= m) {
return odczytaj(sr + 1, k, m, r[i], r[i2]);
} else {
return (pst[r[i]].nd - pst[r[i2]].nd) + odczytaj(p, sr, m - (pst[r[i]].st - pst[r[i2]].st), l[i], l[i2]);
}
}
ll licz (int p, int k) {
return odczytaj(0, int(vec.size()) - 1, M, korzen[k], korzen[p - 1]) - 2LL * (a[k].st - a[p].st);
}
void dziel (int p, int k, int a, int b) {
if (p > k) {
return;
}
int sr = (p + k)/ 2;
int ind = 0;
for (int i = a; i <= b; i ++) {
if ((sr - i + 1) < M) {
break;
}
ll w = licz(i, sr);
if (w > wyn[sr]) {
wyn[sr] = w;
ind = i;
}
}
dziel(p, sr - 1, a, ind);
dziel(sr + 1, k, max(1, ind), b);
}
int main () {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n;
cin >> n >> M;
for (int i = 1; i <= n; i ++) {
cin >> a[i].nd >> a[i].st;
}
sort(a + 1, a + n + 1);
for (int i = 1; i <= n; i ++) {
vec.pb(a[i].nd);
}
sort(vec.begin(), vec.end());
vec.erase(unique(vec.begin(), vec.end()), vec.end());
int k = int(vec.size());
buduj(0, k - 1, 1);
korzen[0] = 1;
for (int i = 1; i <= n; i ++) {
cnt ++;
korzen[i] = cnt;
aktualizuj(0, k - 1, f(a[i].nd), a[i].nd, korzen[i], korzen[i - 1]);
}
for (int i = 1; i <= n; i ++) {
wyn[i] = INF;
}
dziel(1, n, 1, n);
ll w = INF;
for (int i = 1; i <= n; i ++) {
w = max(w, wyn[i]);
}
cout << w << "\n";
return 0;
}
