#include <bits/stdc++.h>
using namespace std;
struct ab {
int a, b;
};
struct event {
int type, val, t;
};
int m;
const int MAX_N = 2e5;
const int MAX_EVENTS = 1e6;
const long long INF = 1e18;
ab v[MAX_N + 1];
int timee = 0;
long long sumA;
vector<event> events, newEvents;
bool inS[MAX_N + 1];
struct pos {
int p;
bool operator < ( const pos q ) const {
return v[p].a < v[q.p].a;
}
};
set<pos> s;
void insertt( int x ) {
inS[x] = true;
s.insert( { x } );
sumA += v[x].a;
newEvents.push_back( { 1, x, ++timee } );
}
void erasee( int x ) {
inS[x] = false;
s.erase( { x } );
sumA -= v[x].a;
newEvents.push_back( { -1, x, ++timee } );
}
void addNewEvents() {
for ( event e: newEvents )
events.push_back( e );
}
void rollback( int t ) {
while ( !events.empty() && events.back().t > t ) {
if (events.back().type == 1 )
erasee( events.back().val );
else
insertt( events.back().val );
events.pop_back();
}
addNewEvents();
}
long long solve( int ll, int lr, int rl, int rr ) {
if ( ll > lr )
return -INF;
int l = (ll + lr) / 2;
long long answer = -INF;
int bestR = rr;
int t = timee;
for ( int i = l; i <= lr && i < rl; i++ ) {
insertt( { i } );
if ( s.size() > m )
erasee( s.begin()->p );
}
addNewEvents();
sumA = 0;
for ( int r = max( l, rl ); r <= rr; r++ ) {
insertt( { r } );
if ( s.size() > m )
erasee( s.begin()->p );
if ( s.size() >= m ) {
if ( sumA - 2 * (v[r].b - v[l].b) > answer ) {
answer = sumA - 2 * (v[r].b - v[l].b);
bestR = r;
}
}
}
addNewEvents();
rollback( t );
for ( int i = min( rl - 1, lr ); i >= l; i-- ) {
insertt( { i } );
if ( s.size() > m )
erasee( s.begin()->p );
}
addNewEvents();
answer = max( answer, solve( ll, l - 1, rl, bestR ) );
rollback( t );
for ( int i = max( lr + 1, rl - 1 ); i < bestR; i++ ) {
insertt( { i } );
if ( s.size() > m )
erasee( s.begin()->p );
}
addNewEvents();
answer = max( answer, solve( l + 1, lr, bestR, rr ) );
rollback( t );
return answer;
}
int main() {
int n;
cin >> n >> m;
for ( int i = 1; i <= n; i++ )
cin >> v[i].a >> v[i].b;
sort( v + 1, v + 1 + n, []( ab x, ab y ) {
return x.b < y.b;
} );
cout << solve( 1, n, 1, n );
return 0;
}
