#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
const bool typetest = 0;
const int N = 2e5 + 5;
const ll Inf = 1e17;
struct Pakage
{
int c;
ll v;
bool operator<(const Pakage &a) const
{
return c < a.c;
}
} a[N];
int n, m, id[N], now[N];
ll dp[N], ans(0);
struct node
{
int v;
ll sum;
node()
{
v = sum = 0;
}
void combine(const node &a, const node &b)
{
v = a.v + b.v;
sum = a.sum + b.sum;
}
};
struct SegmentTree
{
node st[N * 4];
bool ck[N];
SegmentTree()
{
memset(ck, 0, sizeof ck);
}
void Update(int id, int l, int r, int pos, ll v)
{
if (l > pos || r < pos)
return;
if (l == pos && l == r)
{
st[id].v ^= 1;
st[id].sum += v;
return;
}
Update(id << 1, l, (l + r) / 2, pos, v);
Update(id << 1 | 1, (l + r) / 2 + 1, r, pos, v);
st[id].combine(st[id << 1], st[id << 1 | 1]);
}
void Update(int v)
{
Update(1, 1, n, v, (ck[v] ? -1 : 1) * a[id[v]].v);
ck[v] ^= 1;
}
ll Get(int id, int l, int r, int d)
{
if (l == r)
return st[id].sum;
if (st[id << 1].v >= d)
return Get(id << 1, l, (l + r) / 2, d);
else
return st[id << 1].sum + Get(id << 1 | 1, (l + r) / 2 + 1, r, d - st[id << 1].v);
}
ll Get(int d)
{
if (d <= 0)
return 0;
return Get(1, 1, n, d);
}
} f;
void Read()
{
cin >> n >> m;
for (int i = 1; i <= n; ++i)
{
cin >> a[i].v >> a[i].c;
id[i] = i;
}
sort(a + 1, a + n + 1);
sort(id + 1, id + n + 1, [&](const int &x, const int &y) {
return a[x].v > a[y].v;
});
}
template <class T>
void Max(T &x, const T &y)
{
if (x < y)
x = y;
}
void DAC(int l, int r, int optl, int optr)
{
if (l > r)
return;
int mid = (l + r) / 2, optmid(-1);
for (int i = r; i >= mid; --i)
f.Update(now[i]);
for (int i = optl; i <= optr && i < mid - (m - 2); ++i)
{
f.Update(now[i]);
ll v = f.Get(m - 2);
if (dp[mid] < a[mid].v - 2 * a[mid].c + a[i].v + 2 * a[i].c + v)
{
dp[mid] = a[mid].v - 2 * a[mid].c + a[i].v + 2 * a[i].c + v;
optmid = i;
}
}
Max(ans, dp[mid]);
if (optmid != -1)
{
for (int i = optl; i <= optr && i < mid - (m - 2); ++i)
f.Update(now[i]);
DAC(l, mid - 1, optl, optmid);
for (int i = r; i >= mid; --i)
f.Update(now[i]);
for (int i = 1; i < optmid; ++i)
f.Update(now[i]);
DAC(mid + 1, r, optmid, optr);
for (int i = 1; i < optmid; ++i)
f.Update(now[i]);
}
else
{
for (int i = r; i >= mid; --i)
f.Update(now[i]);
DAC(mid + 1, r, optl, optr);
}
}
void Solve()
{
for (int i = 1; i <= n; ++i)
now[id[i]] = i,
f.Update(i);
fill_n(dp, N, -Inf);
ans = -Inf;
DAC(1, n, 1, n);
cout << ans;
}
int32_t main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t(1);
if (typetest)
cin >> t;
for (int _ = 1; _ <= t; ++_)
{
Read();
Solve();
}
}
