#include <stack>
#include <string>
#include <iostream>
#include <stdio.h>
#include <set>
#include <vector>
#include <algorithm>
#include <map>
#include <fstream>

using namespace std;

int main() {
    long long n, d;
    cin >> n >> d;
    vector <pair <long long, long long> > f(n);
    vector <long long> sum(n);
    vector <long long> mon(n);
    for (int i = 0; i < n; ++i) {
        long long  m, s;
        cin >> m >> s;
        f[i] = {m , s};
        mon[i] = m;
    }
    sort(f.begin(), f.end());
    sort(mon.begin(), mon.end());
    sum[0] = f[0].second;
    for (int i = 1; i < n; ++i) {
        sum[i] = sum[i - 1] + f[i].second;
    }
    long long ans = 0;
    for (int i = 0 ; i < n; ++i) {
        auto it = lower_bound(mon.begin(), mon.end(), mon[i] + d) - mon.begin();
        --it;
        long long cur = 0;
        if (i == 0) {
            cur = sum[it];
        }
        else {
            cur = sum[it] - sum[i -1];
        }
        ans = max(ans, cur);
    }
    cout << ans;
}