#include <bits/stdc++.h>
using namespace std;
void setup()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
}
struct FENWICK_TREE
{
long long val[200001];
int num[200001];
inline void Add(int x, int v)
{
while (x <= 2e5)
{
val[x] += v;
num[x]++;
x += (x & (~(x - 1)));
}
}
inline void Remove(int x, int v)
{
while (x <= 2e5)
{
val[x] -= v;
num[x]--;
x += (x & (~(x - 1)));
}
}
inline long long Get(int x)
{
long long res = 0, p = 0;
for (int i = 19; i >= 0; --i)
{
if (p + (1 << i) <= 2e5 && num[p + (1 << i)] <= x)
{
p += (1 << i);
res += val[p];
x -= num[p];
}
}
return (x > 0 ? -1e18 : res);
}
} ft;
int n, m;
array<int, 3> a[200000];
long long f[200000];
inline bool Comp(const array<int, 3> &ina, const array<int, 3> &inb)
{
return ina[1] < inb[1];
}
// Fenwick tree store data from lp to r
inline void Move(int l, int r, int nl, int nr)
{
while (l < nl)
{
ft.Remove(a[l][2], a[l][0]);
l++;
}
while (nl < l)
{
l--;
ft.Add(a[l][2], a[l][0]);
}
while (nr < r)
{
ft.Remove(a[r][2], a[r][0]);
r--;
}
while (r < nr)
{
r++;
ft.Add(a[r][2], a[r][0]);
}
}
inline void Form(int l, int r, int lp, int rp)
{
int opt = lp, mid = (l + r) >> 1, p = min(mid - m + 1, rp);
Move(lp, r, lp, mid);
for (int i = lp; i <= p; ++i)
{
if (f[mid] < ft.Get(m) - 2 * (a[mid][1] - a[i][1]))
{
f[mid] = ft.Get(m) - 2 * (a[mid][1] - a[i][1]);
opt = i;
}
Move(i, mid, i + 1, mid);
}
Move(p + 1, mid, lp, mid - 1);
if (l <= mid - 1)
{
Form(l, mid - 1, lp, opt);
}
Move(lp, mid - 1, opt, r);
if (mid + 1 <= r)
{
Form(mid + 1, r, opt, rp);
}
Move(opt, r, lp, r);
}
int main()
{
setup();
cin >> n >> m;
fill_n(f, n, -1e18);
for (int i = 0; i < n; ++i)
{
cin >> a[i][0] >> a[i][1];
}
sort(a, a + n, greater<array<int, 3>>());
for (int i = 0; i < n; ++i)
{
a[i][2] = i + 1;
ft.Add(a[i][2], a[i][0]);
}
sort(a, a + n, Comp);
Form(m - 1, n - 1, 0, n - m);
cout << (*max_element(f, f + n));
return 0;
}
