#include <bits/stdc++.h>
using namespace std;
long long MAX = 1000000000;
long long MOD = 1000000007;
pair<long long, long long> p[100010];
void solve() {
  long long n;
  cin >> n;
  long long d;
  cin >> d;
  ;
  for (long long i = (0); i < (n); i++) {
    long long in1;
    cin >> in1;
    long long in2;
    cin >> in2;
    ;
    p[i] = {in1, in2};
  }
  sort(p, p + n);
  long long j = 0, sum = 0, ans = 0;
  for (long long i = (0); i < (n); i++) {
    while (p[j].first - p[i].first < d and j < n) {
      sum += p[j].second;
      j++;
    }
    ans = max(ans, sum);
    sum -= p[i].second;
  }
  cout << ans;
}
int main() {
  ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  long long test = 1;
  while (test--) {
    solve();
  }
}
