#include <bits/stdc++.h>
//#define int long long
#define fi first
#define se second
#define pb push_back
#define faster ios_base::sync_with_stdio(0); cin.tie(0);
using namespace std;
using ll = long long;
using ull = unsigned ll;
using ld = long double;
using pii = pair <int, int>;
using pil = pair <int, ll>;
using pli = pair <ll, int>;
using pll = pair <ll, ll>;
mt19937 Rand(chrono::steady_clock::now().time_since_epoch().count());
ll min(const ll &a, const ll &b){
return (a < b) ? a : b;
}
ll max(const ll &a, const ll &b){
return (a > b) ? a : b;
}
//const ll Mod = 1000000007;
//const ll Mod2 = 999999999989;
//only use when required
const int maxN = 1e5 + 1;
int n, m;
int node_cnt = 1;
vector <int> val[maxN * 4];
vector <ll> sum[maxN * 4];
vector <int> b;
ll pre[maxN];
struct TNode{
int l, r;
int lp, rp;
TNode(){
l = r = lp = rp = 0;
}
TNode(int _l, int _r){
l = _l;
r = _r;
}
};
TNode wt[maxN * 4];
void build(int id, auto i, auto j, int l, int r){
wt[id].l = l;
wt[id].r = r;
if (l == r){
return;
}
val[id].pb(0);
sum[id].pb(0);
int mid = (l + r - (l + r < 0)) / 2;
int maxx = l;
int minn = r;
for (auto it = i; it != j; ++it){
val[id].pb(val[id].back() + (*it <= mid));
sum[id].pb(sum[id].back() + *it * (*it <= mid));
if (*it <= mid) maxx = max(maxx, *it);
else minn = min(minn, *it);
}
auto p = stable_partition(i, j,[=](const auto &w){
return w <= mid;
});
wt[id].lp = ++node_cnt;
wt[id].rp = ++node_cnt;
build(wt[id].lp, i, p, l, maxx);
build(wt[id].rp, p, j, minn, r);
}
ll get(int k, int i, int j){
if (k == 0) return 0;
--i;
ll res = 0;
int id = 1;
int l = wt[id].l, r = wt[id].r;
while (l < r){
int mid = (l + r) / 2;
if (k <= val[id][j] - val[id][i]){
i = val[id][i];
j = val[id][j];
id = wt[id].lp;
}
else{
res += sum[id][j] - sum[id][i];
k -= val[id][j] - val[id][i];
i -= val[id][i];
j -= val[id][j];
id = wt[id].rp;
}
l = wt[id].l, r = wt[id].r;
}
res += k * l;
return res;
}
struct TCake{
int v, c;
bool operator < (const TCake &other) const{
return c < other.c;
}
};
TCake a[maxN];
ll bs(int l, int r, int t){
ll x = get(m, l, t) + 2 * a[l].c;
while (l <= r){
int mid = (l + r) / 2;
ll y = get(m, mid, t) + 2 * a[mid].c;
if (y >= x){
x = y;
l = mid + 1;
}
else r = mid - 1;
}
return get(m, r, t) + 2 * a[r].c;
}
void Init(){
cin >> n >> m;
for (int i = 1; i <= n; ++i){
cin >> a[i].v >> a[i].c;
}
sort(a + 1, a + n + 1);
b.resize(n + 1);
for (int i = 1; i <= n; ++i){
b[i] = a[i].v;
}
build(1, b.begin() + 1, b.end(), *min_element(b.begin() + 1, b.end()),
*max_element(b.begin() + 1, b.end()));
ll ans = 0;
for (int i = m; i <= n; ++i){
ll tem = bs(1, i - m + 1, i);
ans = max(ans, tem - 2 * a[i].c);
}
cout << ans;
}
#define debu
#define taskname "test"
signed main(){
if (fopen(taskname".inp", "r")){
freopen(taskname".inp", "r", stdin);
#ifdef debug
freopen(taskname".out", "w", stdout);
#endif
}
faster;
ll tt = 1;
//cin >> tt;
while (tt--){
Init();
}
if (fopen("timeout.txt", "r")){
ofstream timeout("timeout.txt");
timeout << 1000 * double(clock()) / CLOCKS_PER_SEC;
#ifndef debug
cerr << "\nTime elapsed: " << 1000 * double(clock()) / CLOCKS_PER_SEC << "ms\n";
#endif
}
}
