#include <bits/stdc++.h>
#define mp make_pair
#define pb push_back
#define X first
#define Y second
#define y0 y12
#define y1 y22
#define INF 987654321987654321
#define PI 3.141592653589793238462643383279502884
#define fup(i,a,b,c) for(int (i)=(a);(i)<=(b);(i)+=(c))
#define fdn(i,a,b,c) for(int (i)=(a);(i)>=(b);(i)-=(c))
#define MEM0(a) memset((a),0,sizeof(a));
#define MEM_1(a) memset((a),-1,sizeof(a));
#define ALL(a) a.begin(),a.end()
#define SYNC ios_base::sync_with_stdio(false);cin.tie(0)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef double db;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair<int, int> Pi;
typedef pair<ll, ll> Pll;
typedef pair<ld, ld> Pd;
typedef vector<int> Vi;
typedef vector<ll> Vll;
typedef vector<ld> Vd;
typedef vector<Pi> VPi;
typedef vector<Pll> VPll;
typedef vector<Pd> VPd;
typedef tuple<int, int, int> iii;
typedef tuple<int, int, int, int> iiii;
typedef tuple<ll, ll, ll> LLL;
typedef vector<iii> Viii;
typedef vector<LLL> VLLL;
typedef complex<double> base;
const int MOD = 42043;
ll POW(ll a, ll b, ll MMM = MOD) { ll ret = 1; for (; b; b >>= 1, a = (a*a) % MMM)if (b & 1)ret = (ret*a) % MMM; return ret; }
ll gcd(ll a, ll b) { return b ? gcd(b, a%b) : a; }
ll lcm(ll a, ll b) { if (a == 0 || b == 0)return a + b; return a*(b / gcd(a, b)); }
int dx[] = { 0,1,0,-1,1,1,-1,-1 }, dy[] = { 1,0,-1,0,1,-1,1,-1 };
int ddx[] = { -1,-2,1,-2,2,-1,2,1 }, ddy[] = { -2,-1,-2,1,-1,2,1,2 };
Pll p[200000];
bool chk[200000];
set<Pll> S;
ll sum;
int n,m;
int L,R;
void ins(int i)
{
chk[i]=1;
S.insert(mp(p[i].X,i));
sum+=p[i].X;
if(S.size()>m-2)
{
auto P=*S.begin();
sum-=p[P.Y].X;
chk[P.Y]=0;
S.erase(S.begin());
}
}
void era(int i)
{
if(!chk[i])return;
S.erase(S.find(mp(p[i].X,i)));
sum-=p[i].X;
}
ll f(int l,int r)
{
if(r-l+1<m-2)return -INF;
while(r>R)ins(++R);
while(L>l)ins(--L);
while(r<R)era(R--);
while(L<l)era(L++);
return sum;
}
ll g(int S,int E,int l,int r)
{
S=max(S,l+m-1);
if(S>E)return -INF;
int M=S+E>>1;
ll res=-INF;
int w=-1;
fdn(i,min(r,M-m+1),l,1)
{
ll tmp=f(i+1,M-1)+p[i].X+p[M].X-2*(p[M].Y-p[i].Y);
if(tmp>res)res=tmp,w=i;
}
return max({res,g(M+1,E,w,r),g(S,M-1,l,w)});
}
int main() {
scanf("%d%d",&n,&m);
L=R=n-1>>1;
R--;
fup(i,0,n-1,1)scanf("%lld%lld",&p[i].X,&p[i].Y);
sort(p,p+n,[&](Pll p1,Pll p2){return p1.Y<p2.Y;});
printf("%lld\n",g(0,n-1,0,n-1));
}
