//I wrote this code 4 u <3
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#ifdef LOCAL
#include "algo/debug.h"
#else
#define debug(...) 42
#endif
template<typename T> bool ckmax(T& a, T b) { return a < b ? a = b, 1 : 0; }
constexpr ll infl = 0x3f3f3f3f3f3f3f3f;
struct WT {
vector<vector<int>> t, pref;
vector<vector<ll>> sm;
vector<int> srt;
int sz;
WT(vector<int>& a) {
srt = a;
ranges::sort(srt);
srt.resize(unique(srt.begin(), srt.end()) - srt.begin());
sz = 1;
while (sz < (int) srt.size()) sz <<= 1;
t.resize(sz << 1);
sm.resize(sz << 1);
pref.resize(sz << 1);
t[1] = a;
for (auto& x : t[1]) x = lower_bound(srt.begin(), srt.end(), x) - srt.begin();
build(1, 0, srt.size());;
}
void build(int x, int lx, int rx) {
if (lx + 1 == rx) return;
int m = (lx + rx) >> 1;
sm[x].resize(t[x].size() + 1);
pref[x].resize(t[x].size() + 1);
sm[x][0] = pref[x][0] = 0;
for (int i = 0; i < (int) t[x].size(); ++i) {
int v = t[x][i], le = t[x][i] < m;
pref[x][i + 1] = pref[x][i] + le;
sm[x][i + 1] = sm[x][i] + le * srt[v];
if (le) {
t[x << 1].push_back(v);
} else {
t[x << 1 | 1].push_back(v);
}
}
build(x << 1, lx, m);
build(x << 1 | 1, m, rx);
}
ll get(int l, int r, int k, int x, int lx, int rx) {
if (lx + 1 == rx) return 1ll * k * srt[lx];
int m = (lx + rx) >> 1, lb = pref[x][l], rb = pref[x][r], lft = rb - lb;
if (lft >= k) return get(lb, rb, k, x << 1, lx, m);
return sm[x][r] - sm[x][l] + get(l - lb, r - rb, k - lft, x << 1 | 1, m, rx);
}
ll get(int l, int r, int k) {
return get(l, r, k, 1, 0, srt.size());
}
};
signed main(int32_t argc, char *argv[]) {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int N, K;
cin >> N >> K;
vector<array<int, 2>> a(N);
for (int i = 0; i < N; ++i) cin >> a[i][1] >> a[i][0];
sort(a.begin(), a.end());
vector<int> val(N);
for (int i = 0; i < N; ++i) {
val[i] = -a[i][1];
}
WT tt(val);
auto cost = [&](int l, int r) { // [l, r]
return 2 * a[l][0] - 2 * a[r][0] + a[l][1] + a[r][1] - tt.get(l + 1, r, K - 2);
};
ll ans = -infl;
auto divi = [&](auto&& self, int lx, int rx, int optl, int optr) {
if (lx > rx) return;
int m = (lx + rx) >> 1, opt = max(0, m - K + 1);
if (m - K + 1 > -1) {
ll nw = cost(opt, m);
for (int i = optl; i <= min(m - K + 1, optr); ++i) {
if (ckmax(nw, cost(i, m))) opt = i;
}
ans = max(ans, nw);
self(self, lx, m - 1, optl, opt);
}
self(self, m + 1, rx, opt, optr);
};
divi(divi, 0, N - 1, 0, N - 1);
cout << ans;
}
/*
*/
