#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define fs first
#define sc second
using namespace std;
const ll N = 3e5 + 69;
const ll mod = 1e16 + 7;
typedef pair<ll,ll> LL;
ll n,m,id[N],cur = 1,lf = 1,rg = 1;
LL a[N],b[N];
struct Node{
ll val,on;
};
Node st[4*N];
Node operator + (Node a,Node b){
Node c = {a.val + b.val,a.on + b.on};
return c;
}
void upd(ll id,ll l,ll r,ll u,ll v){
if (u < l||r < u) return;
if (l == r){
st[id].val += v;
if (v > 0) st[id].on++;
else st[id].on--;
return;
}
ll mid = (l + r)/2;
upd(id*2,l,mid,u,v); upd(id*2 + 1,mid + 1,r,u,v);
st[id] = st[id*2] + st[id*2 + 1];
}
ll Get(ll id,ll l,ll r,ll cnt){
if (st[id].on <= cnt) return st[id].val;
ll mid = (l + r)/2;
if (st[id*2].on <= cnt) return st[id*2].val + Get(id*2 + 1,mid + 1,r,cnt - st[id*2].on);
return Get(id*2,l,mid,cnt);
}
bool lessf(LL x,LL y){
return x.sc < y.sc;
}
ll process(ll l,ll r){
while(rg <= r){
upd(1,1,n,id[rg],a[rg].fs); rg++;
}
while(rg > r){
upd(1,1,n,id[rg],-a[rg].fs); rg--;
}
while(lf >= l){
upd(1,1,n,id[lf],a[lf].fs); lf--;
}
while(lf < l){
upd(1,1,n,id[lf],-a[lf].fs); lf++;
}
return Get(1,1,n,m);
}
ll final_ans = -mod;
void f(ll L,ll R,ll fday,ll lday){
ll now = (fday + lday)/2,pos = R,cur_ans = -mod;
if (fday > lday) return;
for (ll i = now;i <= min(R,n);i++){
ll kq = process(now,i) - 2*(a[i].sc - a[now].sc);
//cout<<Get(1,1,n,m)<<" "<<now<<" "<<i<<"\n";
if (i - now + 1 >= m){
if (kq > cur_ans) cur_ans = kq,pos = i;
}
}
//cout<<a[now + 1].fs;
//exit(0);
//for (ll i = now;i <= min(R,n);i++) upd(1,1,n,id[i],0);
final_ans = max(final_ans,cur_ans);
f(L,pos,fday,now - 1); f(pos,R,now + 1,lday);
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
#define task "test"
if (fopen(task".INP","r")){
freopen(task".INP","r",stdin);
freopen(task".OUT","w",stdout);
}
cin>>n>>m;
for (ll i = 1;i <= n;i++) cin>>a[i].fs>>a[i].sc; sort(a + 1,a + n + 1,lessf);
for (ll i = 1;i <= n;i++) b[i].fs = a[i].fs,b[i].sc = i; sort(b + 1,b + n + 1,greater<LL>());
for (ll i = 1;i <= n;i++) id[b[i].sc] = i;
f(1,n,1,n);
cout<<final_ans;
}
