#include <bits/stdc++.h>
using namespace std;
namespace std {
template<class Fun>
class y_combinator_result {
Fun fun_;
public:
template<class T>
explicit y_combinator_result(T &&fun): fun_(std::forward<T>(fun)) {}
template<class ...Args>
decltype(auto) operator()(Args &&...args) {
return fun_(std::ref(*this), std::forward<Args>(args)...);
}
};
template<class Fun>
decltype(auto) y_combinator(Fun &&fun) {
return y_combinator_result<std::decay_t<Fun>>(std::forward<Fun>(fun));
}
} // namespace std
class wavelet_tree {
int n;
vector<long long> vmap;
vector<vector<int>> tree;
vector<vector<long long>> psum;
template<typename I>
void build(I begin, I end, int t, int vl, int vr) {
if (vl == vr) {
int nn = end - begin + 1;
psum[t].reserve(nn);
psum[t].push_back(0);
for (auto it = begin; it != end; it++)
psum[t].push_back(psum[t].back() + vmap[*it]);
return;
}
int vm = (vl + vr) / 2, nn = end - begin + 1;
tree[t].reserve(nn);
psum[t].reserve(nn);
tree[t].push_back(0);
psum[t].push_back(0);
for (auto it = begin; it != end; it++) {
tree[t].push_back(tree[t].back() + (*it <= vm));
psum[t].push_back(psum[t].back() + vmap[*it]);
}
auto pivot = stable_partition(begin, end, [vm](int x) { return x <= vm; });
build(begin, pivot, t * 2, vl, vm);
build(pivot, end, t * 2 + 1, vm + 1, vr);
}
long long query(int l, int r, int k, int t, int vl, int vr) {
if (vl == vr)
return k * vmap[vl];
int vm = (vl + vr) / 2, lv = tree[t][r] - tree[t][l - 1];
if (k <= lv){
return query(tree[t][l - 1] + 1, tree[t][r], k, t * 2, vl, vm);
} else {
return psum[t * 2][tree[t][r]] - psum[t * 2][tree[t][l - 1]] +\
query(l - tree[t][l - 1], r - tree[t][r], k - lv, t * 2 + 1, vm + 1, vr);
}
}
public:
wavelet_tree(vector<long long> vec) { init(vec.begin(), vec.end()); }
template<typename I>
void init(I begin, I end) {
map<long long, int> m;
for (auto it = begin; it != end; it++)
m[*it] = 0;
n = 0;
vmap.resize(m.size());
for (auto &[k, v] : m)
vmap[v = n++] = k;
for (auto it = begin; it != end; it++)
*it = m[*it];
tree.resize(4 * n);
psum.resize(4 * n);
build(begin, end, 1, 0, n);
}
// returns sum of k smallest elements in range [l, r]
long long query(int l, int r, int k) {
assert(k <= r - l + 1);
return query(l + 1, r + 1, k, 1, 0, n);
}
};
int main() {
int N, M;
cin >> N >> M;
vector<pair<long long, long long>> A(N);
for (auto &[v, c] : A) {
cin >> v >> c;
v = -v;
}
sort(A.begin(), A.end(), [](auto a, auto b) {
return a.second < b.second;
});
vector<long long> V(N), C(N);
for (int i = 0; i < N; i++) {
tie(V[i], C[i]) = A[i];
}
wavelet_tree wt(V);
vector<int> rpos(N - M + 1);
y_combinator([&](auto self, int pl, int pr, int ql, int qr) -> void {
if (pr < pl) {
return;
}
if (ql == qr) {
for (int i = pl; i <= pr; i++)
rpos[i] = ql;
return;
}
int pm = (pl + pr) / 2, qm = -1;
long long val = LLONG_MIN;
for (int i = ql; i <= qr; i++) {
if (i - pm + 1 < M) {
continue;
}
long long cur = -wt.query(pm, i, M) - 2 * (C[i] - C[pm]);
if (val < cur) {
val = cur;
qm = i;
}
}
rpos[pm] = qm;
self(pl, pm - 1, ql, qm);
self(pm + 1, pr, qm, qr);
})(0, N - M, M - 1, N - 1);
long long ans = LLONG_MIN;
for (int l = 0; l < N - M + 1; l++) {
int r = rpos[l];
long long val = -wt.query(l, r, M) - 2 * (C[r] - C[l]);
ans = max(ans, val);
}
cout << ans << '\n';
}
