/*
* @Author: hungeazy
* @Date: 2024-06-08 18:44:05
* @Last Modified by: hungeazy
* @Last Modified time: 2024-06-08 18:51:55
*/
#include <bits/stdc++.h>
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")
using namespace std;
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define int long long
#define ull unsigned long long
#define sz(x) x.size()
#define sqr(x) (1LL * (x) * (x))
#define all(x) x.begin(), x.end()
#define fill(f,x) memset(f,x,sizeof(f))
#define FOR(i,l,r) for(int i=l;i<=r;i++)
#define FOD(i,r,l) for(int i=r;i>=l;i--)
#define ii pair<int,int>
#define iii pair<int,ii>
#define di pair<ii,ii>
#define vi vector<int>
#define vii vector<ii>
#define mii map<int,int>
#define fi first
#define se second
#define pb push_back
#define MOD 1000000007
#define __lcm(a,b) (1ll * ((a) / __gcd((a), (b))) * (b))
#define YES cout << "YES\n"
#define NO cout << "NO\n"
#define MASK(i) (1LL << (i))
#define c_bit(i) __builtin_popcountll(i)
#define BIT(x,i) ((x) & MASK(i))
#define SET_ON(x,i) ((x) | MASK(i))
#define SET_OFF(x,i) ((x) & ~MASK(i))
#define oo 1e18
#define name "EMISTA"
#define endl '\n'
#define time() cout << "-------------Time:" << 1000.0 * clock() / CLOCKS_PER_SEC << "ms.";
template<typename T> bool maximize(T &res, const T &val) { if (res < val){ res = val; return true; }; return false; }
template<typename T> bool minimize(T &res, const T &val) { if (res > val){ res = val; return true; }; return false; }
const int N = (int)1e6+10;
ii a[N];
int pre[N];
signed main()
{
fast;
// freopen(name".inp","r",stdin);
// freopen(name".out","w",stdout);
int n,k;
cin >> n >> k;
FOR(i,1,n) cin >> a[i].fi >> a[i].se;
sort(a+1,a+n+1);
FOR(i,1,n) pre[i] = pre[i-1]+a[i].se;
int ans = 0;
FOR(i,1,n)
{
int l = i, r = n, pos;
while (l <= r)
{
int mid = (l+r)>>1;
if (a[i].fi+2*k >= a[mid].fi) pos = mid, l = mid+1;
else r = mid-1;
}
ans = max(ans,pre[pos]-pre[i-1]);
}
cout << ans;
return 0;
}
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