#include <bits/stdc++.h>
#define pb push_back
#define all(v) ((v).begin(), (v).end())
#define sortv(v) sort(all(v))
#define sz(v) ((int)(v).size())
#define uniqv(v) (v).erase(unique(all(v)), (v).end())
#define umax(a, b) (a)=max((a), (b))
#define umin(a, b) (a)=min((a), (b))
#define FOR(i,a,b) for(int i = (a); i <= (b); i++)
#define rep(i,n) FOR(i,1,n)
#define rep0(i,n) FOR(i,0,(int)(n)-1)
#define FI first
#define SE second
#define INF 2000000000
#define INFLL 1000000000000000000LL
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
int N, M;
vector<pll> vt;
ll ans = -INFLL;
priority_queue<ll> pq1, pq2;
int sz = 0;
struct PST{
struct NODE{
int l, r;
int cnt;
ll sum;
};
int SZ;
vector<NODE> seg;
vector<int> Tree;
void Init(int x){
SZ = x;
Tree.pb(0);
seg.pb({-1, -1, 0, 0});
init(Tree[0], 0, SZ-1);
}
void init(int idx, int s, int e){
if(s==e) return;
seg[idx].l = seg.size(); seg.pb({-1, -1, 0, 0});
seg[idx].r = seg.size(); seg.pb({-1, -1, 0, 0});
init(seg[idx].l, s, (s+e)/2); init(seg[idx].r, (s+e)/2+1, e);
}
void Update(int x, ll y){
Tree.pb(update(Tree.back(), 0, SZ-1, x, y));
}
int update(int pidx, int s, int e, int x, ll y){
if(x<s || x>e) return pidx;
int idx = seg.size(); seg.pb({-1, -1, 0, 0});
if(s==e){
seg[idx].sum = y; seg[idx].cnt = 1;
return idx;
}
int k = update(seg[pidx].l, s, (s+e)/2, x, y); seg[idx].l = k;
k = update(seg[pidx].r, (s+e)/2+1, e, x, y); seg[idx].r = k;
seg[idx].sum = seg[seg[idx].l].sum + seg[seg[idx].r].sum;
seg[idx].cnt = seg[seg[idx].l].cnt + seg[seg[idx].r].cnt;
return idx;
}
int Cnt(int x, int y, int z){
return calc_cnt(Tree[x], 0, SZ-1, y, z);
}
int calc_cnt(int idx, int s, int e, int x, int y){
if(x<=s && e<=y) return seg[idx].cnt;
if(x>e || y<s) return 0;
return calc_cnt(seg[idx].l, s, (s+e)/2, x, y) + calc_cnt(seg[idx].r, (s+e)/2+1, e, x, y);
}
ll Sum(int x, int y, int z){
return calc_sum(Tree[x], 0, SZ-1, y, z);
}
ll calc_sum(int idx, int s, int e, int x, int y){
if(x<=s && e<=y) return seg[idx].sum;
if(x>e || y<s) return 0;
return calc_sum(seg[idx].l, s, (s+e)/2, x, y) + calc_sum(seg[idx].r, (s+e)/2+1, e, x, y);
}
};
PST Pst;
ll csum(int x, int y){
int s = 1, e = N, m;
while(s<e){
m = (s+e)/2;
int k = Pst.Cnt(m, x, y);
if(k==M){
//cout<<m<<" "<<x<<" "<<y<<" "<<Pst.Sum(m, x, y)<<endl;
return Pst.Sum(m, x, y);
}
if(k<M){
s = m+1;
}else{
e = m-1;
}
}
return Pst.Cnt(s, x, y);
}
void calc(int x, int y, int s, int e){
if(x>y) return;
int m = (x+y)/2;
ll mx = -INFLL, idx = 0;
for(int i=s; i<=e; i++){
if(m-i+1<M) continue;
ll c = csum(i, m);
if(mx < c - 2 * (vt[m].first - vt[i].first)){
mx = c - 2 * (vt[m].first - vt[i].first);
idx = i;
}
}
ans = max(ans, mx);
calc(x, m-1, s, idx); calc(m+1, y, idx, e);
}
vector<pll> upd;
int main(){
scanf("%d%d", &N, &M);
for(int i=0; i<N; i++){
ll a, b;
scanf("%lld%lld", &a, &b);
vt.pb({b, a});
}
sort(vt.begin(), vt.end());
for(int i=0; i<N; i++){
upd.pb({vt[i].second, i});
}
sort(upd.begin(), upd.end());
Pst.Init(N);
while(!upd.empty()){
Pst.Update(upd.back().second, upd.back().first);
upd.pop_back();
}
calc(0, N-1, 0, N-1);
cout<<ans;
return 0;
}
