#include <bits/stdc++.h>

using namespace std;

long long n, m, d, i, ans;
pair<long long, long long> a[100005];

int main() {
#ifndef ONLINE_JUDGE
  freopen("input.txt", "r", stdin);
#else
#endif
  scanf("%lld %lld", &n, &d);
  for (i = 0; i < n; i++) {
    long long k, x;
    scanf("%lld %lld", &k, &x);
    a[i] = make_pair(k, x);
  }
  ans = LLONG_MIN;
  sort(a, a + n);
  vector <long long> pref(n+1);
  long long sum = 0;
  for (i = 0; i <= n; i++) {
    pref[i] = sum;
    sum += a[i].second;
  }
  long long bb = 0, tp = 0;
  for (i = 0; i < n; i++) {
    while (a[i].first + d - 1 >= a[tp].first && tp<n)
      tp++;
    ans = max(ans, pref[tp] - pref[i]);
  }
  printf("%lld\n", ans);
  return 0;
}