#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int MAXN = 2e5;
struct Cake
{
int V, C;
bool operator < (const Cake &p) { return C<p.C; }
}A[MAXN+10];
int N, M, S;
ll ans=-1e18;
vector<int> comp;
int getcomp(int x) { return lower_bound(comp.begin(), comp.end(), x)-comp.begin(); }
struct Node
{
int cnt; ll sum;
Node *lc, *rc;
Node() : cnt(0), sum(0), lc(NULL), rc(NULL) {}
};
Node *tree[MAXN+10];
void makeTree(Node *node, int tl, int tr)
{
if(tl==tr) return;
int mid=tl+tr>>1;
node->lc=new Node();
node->rc=new Node();
makeTree(node->lc, tl, mid);
makeTree(node->rc, mid+1, tr);
}
Node *addTree(Node *node, int tl, int tr, int pos)
{
if(pos<tl || tr<pos) return node;
Node *ret=new Node();
if(tl==tr)
{
ret->cnt=node->cnt+1;
ret->sum=node->sum+comp[tl];
return ret;
}
int mid=tl+tr>>1;
ret->lc=addTree(node->lc, tl, mid, pos);
ret->rc=addTree(node->rc, mid+1, tr, pos);
ret->cnt=ret->lc->cnt+ret->rc->cnt;
ret->sum=ret->lc->sum+ret->rc->sum;
return ret;
}
ll query(Node *nodel, Node *noder, int tl, int tr, int k)
{
if(tl==tr) return comp[tl]*min(k, noder->cnt-nodel->cnt);
int mid=tl+tr>>1;
int t=noder->rc->cnt-nodel->lc->cnt;
if(k>t) return query(nodel->lc, noder->lc, tl, mid, k-t)+noder->rc->sum-nodel->rc->sum;
else return query(nodel->rc, noder->rc, mid+1, tr, k);
}
void solve(int sl, int sr, int el, int er)
{
if(sl>sr) return;
int i, j;
int smid=sl+sr>>1, emid; ll val=-1e18;
for(i=max(smid+M-1, el); i<=er; i++)
{
ll now=query(tree[smid-1], tree[i], 0, S-1, M)-2*(A[i].C-A[smid].C);
if(now>val) val=now, emid=i;
}
ans=max(ans, val);
solve(sl, smid-1, el, emid);
solve(smid+1, sr, emid, er);
}
int main()
{
int i, j;
scanf("%d%d", &N, &M);
for(i=1; i<=N; i++) scanf("%d%d", &A[i].V, &A[i].C), comp.push_back(A[i].V);
sort(A+1, A+N+1);
sort(comp.begin(), comp.end());
comp.erase(unique(comp.begin(), comp.end()), comp.end());
S=comp.size();
tree[0]=new Node();
makeTree(tree[0], 0, S-1);
for(i=1; i<=N; i++) tree[i]=addTree(tree[i-1], 0, S-1, getcomp(A[i].V));
solve(1, N, 1, N);
printf("%lld", ans);
}
