#include<bits/stdc++.h>
#define taskname "A"
using namespace std;
typedef long long ll;
const ll INF = 1e18;
template<class T>bool maximize(T& a, T b){
if(a < b){
a = b;
return true;
}
return false;
}
int n, m;
namespace sub12{
void solve(){
vector<pair<int, int>>a(n);
for(auto& [c, v] : a){
cin >> v >> c;
}
sort(a.begin(), a.end());
ll ans = -INF;
for(int l = 0; l < n; l++){
priority_queue<int>pq;
ll cur = 0;
for(int r = l; r < n; r++){
cur += a[r].second;
pq.push(-a[r].second);
if(pq.size() > m){
cur += pq.top();
pq.pop();
}
if(r - l + 1 >= m){
maximize(ans, cur - ((a[r].first - a[l].first) << 1));
}
}
}
cout << ans;
}
}
namespace sub3{
const int lim = 2e5 + 5;
pair<int, int>a[lim];
int l = 1, r = 0, comv[lim], bit_c[lim];
ll ans = -INF, bit_s[lim];
void add(int p, int x){
for(; p <= n; p += p & -p){
bit_c[p]++;
bit_s[p] += x;
}
}
void sub(int p, int x){
for(; p <= n; p += p & -p){
bit_c[p]--;
bit_s[p] -= x;
}
}
ll query(int lq, int rq){
while(r < rq){
r++;
add(comv[r], a[r].second);
}
while(r > rq){
sub(comv[r], a[r].second);
r--;
}
while(l < lq){
sub(comv[l], a[l].second);
l++;
}
while(l > lq){
l--;
add(comv[l], a[l].second);
}
ll sum = 0;
for(int bit = 17, p = 0, rem = m; bit > -1; bit--){
int np = p | (1 << bit);
if(np <= n && rem >= bit_c[np]){
rem -= bit_c[p = np];
sum += bit_s[p];
}
}
return sum - ((a[rq].first - a[lq].first) << 1);
}
void dnc(int l, int r, int opt_l, int opt_r){
if(l > r){
return;
}
int mid = (l + r) >> 1, opt = opt_l;
ll best = -INF;
for(int i = min(mid - m + 1, opt_r); i >= opt_l; i--){
if(maximize(best, query(i, mid))){
opt = i;
}
}
maximize(ans, best);
dnc(l, mid - 1, opt_l, opt);
dnc(mid + 1, r, opt, opt_r);
}
void solve(){
for(int i = 1; i <= n; i++){
cin >> a[i].second >> a[i].first;
}
sort(a + 1, a + n + 1);
vector<int>cv(n);
iota(cv.begin(), cv.end(), 1);
sort(cv.begin(), cv.end(), [&] (int i, int j){
return a[i].second > a[j].second;
});
for(int i = 0; i < n; i++){
comv[cv[i]] = i + 1;
}
memset(bit_c, 0, sizeof(bit_c));
memset(bit_s, 0, sizeof(bit_s));
dnc(1, n, 1, n);
cout << ans;
}
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
if(fopen(taskname".inp", "r")){
freopen(taskname".inp", "r", stdin);
}
cin >> n >> m;
if(n <= 2000){
sub12::solve();
}
else{
sub3::solve();
}
}
