Saengja

/*
    Task    : _example
    Author  : Phumipat C. [MAGCARI]
    Language: C++
    Created : 11 December 2022 [11:55]
*/
#include<bits/stdc++.h>
using namespace std;
struct A{
    long long value;
    int idx;
    bool operator < (const A&o) const{
        return value<o.value;
    }
};
pair<int ,int > restaurant[100010];
// first is position
// second is happy value
priority_queue<A > heap;
int main(){
    int n,k;
    scanf("%d %d",&n,&k);
    for(int i=1;i<=n;i++)
        scanf("%d %d",&restaurant[i].first,&restaurant[i].second);
    sort(restaurant+1,restaurant+n+1);
    long long ans = 0;
    for(int i=1;i<=n;i++){
        int xj = restaurant[i].first;
        int cj = restaurant[i].second;
        long long temp = ans;
        while(!heap.empty() && xj - heap.top().idx > k) heap.pop();
        if(!heap.empty())   ans = max(ans,heap.top().value+cj-xj);
        heap.push({temp+xj+cj,xj});
    }
    printf("%lld\n",ans);
    return 0;
}