#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
const int N = 2e5 + 5;
int n, m;
ll V[N], C[N];
pair<ll, ll> a[N];
int inDex[N];
int nNode, rootVer[N];
ll ans;
struct node {
ll val, cnt, lef, rig;
} st[40 * N];
int build(int l, int r) {
if (l == r) {
int id = ++nNode;
st[id] = {0, 0, 0, 0};
return id;
}
int mid = (l + r) >> 1;
int id = ++nNode;
st[id].lef = build(l, mid);
st[id].rig = build(mid + 1, r);
st[id].val = st[id].cnt = 0;
return id;
}
int update(int old, int l, int r, int i, ll x) {
if (l == r) {
int id = ++nNode;
st[id] = {st[old].val + x, st[old].cnt + 1, st[old].lef, st[old].rig};
return id;
}
int mid = (l + r) >> 1;
int id = ++nNode;
if (i <= mid) {
st[id].lef = update(st[old].lef, l, mid, i, x);
st[id].rig = st[old].rig;
} else {
st[id].lef = st[old].lef;
st[id].rig = update(st[old].rig, mid + 1, r, i, x);
}
st[id].val = st[st[id].lef].val + st[st[id].rig].val;
st[id].cnt = st[st[id].lef].cnt + st[st[id].rig].cnt;
return id;
}
ll get(int idL, int idR, int l, int r, int x) {
if (l == r) {
return st[idR].val - st[idL].val;
} else {
int mid = (l + r) >> 1;
int L = st[idL].lef, R = st[idR].lef;
if (st[R].cnt - st[L].cnt < x) {
ll sum = st[R].val - st[L].val;
ll hav = st[R].cnt - st[L].cnt;
L = st[idL].rig;
R = st[idR].rig;
return sum + get(L, R, mid + 1, r, x - hav);
} else {
return get(L, R, l, mid, x);
}
}
}
void solve(int l, int r, int opL, int opR) {
if (l > r) return;
int mid = (l + r) >> 1;
ll res = -1e18, opt = -1;
for (int i = opL; i <= min(opR, mid - m + 1); i++) {
ll tmp = V[i] + V[mid] + get(rootVer[i], rootVer[mid - 1], 1, n, m - 2) - 2 * (C[mid] - C[i]);
if(tmp > res) {
res = tmp;
opt = i;
}
}
ans = max(ans, res);
solve(l, mid - 1, opL, opt);
solve(mid + 1, r, opt, opR);
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> m;
for (int i = 1; i <= n; i++) {
cin >> a[i].se >> a[i].fi;
}
sort(a + 1, a + 1 + n);
for (int i = 1; i <= n; i++) {
V[i] = a[i].se;
C[i] = a[i].fi;
a[i] = {V[i], i};
}
sort(a + 1, a + 1 + n);
for (int i = 1; i <= n; i++) {
inDex[a[i].se] = n - i + 1;
}
rootVer[0] = build(1, n);
for (int i = 1; i <= n; i++) {
rootVer[i] = update(rootVer[i - 1], 1, n, inDex[i], V[i]);
}
ans = -1e18;
solve(m, n, 1, n);
cout << ans;
}
