#include <bits/stdc++.h>
using namespace std;
int main() {
    int n;
    long long d;
    cin >> n >> d;
    pair <long long,long long> arr[n];
    long long max = 0;
    for(int i = 0; i < n; i++){
        pair <int,int> a;
        cin >> a.first >> a.second;
        arr[i] = a;
    }
    sort(arr,arr+n);
    for(int i = 0; i < n; i++){
        long long cont = arr[i].second;
        for(int j = i+1; j < n; j++){
            if(arr[j].first - arr[i].first < d){
                cont += arr[j].second;
            }
        }
        if(cont > max){
            max = cont;
        }
    }
    cout << max;
    return 0;
}