#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/trie_policy.hpp>
#define pb push_back
#define mp make_pair
#define taskname "A"
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> ii;
typedef tree <ii,null_type,less<ii>,rb_tree_tag,tree_order_statistics_node_update> ordered_set;
const int maxn = 2e5 + 5;
ll s[maxn * 4];
int cnt[maxn * 4];
ll res = 0;
int order[maxn] , id[maxn];
int n , m;
ii a[maxn];
void flip(int x , int l , int r , int pos){
if(l == r){
if(cnt[x] == 0)cnt[x] = 1 , s[x] = a[order[l]].second;
else cnt[x] = 0 , s[x] = 0;
return;
}
int mid = l + r >> 1;
if(pos <= mid)flip(x * 2 , l , mid , pos);
else flip(x * 2 + 1 , mid + 1 , r , pos);
s[x] = s[x * 2] + s[x * 2 + 1];
cnt[x] = cnt[x * 2] + cnt[x * 2 + 1];
}
ll get(int x , int l , int r , int k){
if(cnt[x] <= k)return s[x];
if(l == r || k <= 0)return 0;
ll sum = 0;
int mid = l + r >> 1;
sum += get(x * 2 + 1 , mid + 1 , r , min(k , cnt[x * 2 + 1]));
k -= min(k , cnt[x * 2 + 1]);
sum += get(x * 2 , l , mid , k);
return sum;
}
void flip(int pos){flip(1,1,n,pos);}
ll get(int k){return get(1,1,n,k);};
int L = 1 , R = 0;
void correct(int l , int r){
while(L < l)flip(id[L++]);
while(L > l)flip(id[--L]);
while(R < r)flip(id[++R]);
while(R > r)flip(id[R--]);
}
void solve(int l , int r , int bl , int br){
if(l > r)return;
int mid = l + r >> 1;
pair<ll,int> b = mp(-1e18,mid);
for(int i = bl ; i + m - 1 <= mid && i <= br ; ++i){
correct(i , mid);
b = max(b , mp(get(1,1,n,m) - (a[mid].first - a[i].first) * 2 , i));
}
res = max(res , b.first);
solve(l , mid - 1 , bl , b.second);
solve(mid + 1 , r , b.second , br);
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
if(fopen(taskname".INP","r")){
freopen(taskname".INP", "r",stdin);
freopen(taskname".OUT", "w",stdout);
}
cin >> n >> m;
for(int i = 1 ; i <= n ; ++i){
cin >> a[i].second >> a[i].first;
}
sort(a + 1 , a + n + 1);
iota(order + 1 , order + n + 1 , 1);
sort(order + 1 , order + n + 1 , [&](const int x , const int y){
return a[x].second < a[y].second;
});
for(int i = 1 ; i <= n ; ++i){
id[order[i]] = i;
}
solve(m , n , 1 , n);
cout << res;
}
