package main

import (
	"fmt"
)

const N = 200005

var a, b [N]pair

type pair struct{ m, s int }

func Max(i, j int) int {
	if i >= j {
		return i
	} else {
		return j
	}
}

func mergeSort(l, r int) {
	if l >= r {
		return
	}
	mid := (l + r) / 2
	mergeSort(l, mid)
	mergeSort(mid+1, r)
	i, j := l, mid+1

	pos := l
	for i <= mid || j <= r {
		if i == mid+1 {
			b[pos] = a[j]
			j++
		} else if j == r+1 {
			b[pos] = a[i]
			i++
		} else if a[i].m < a[j].m {
			b[pos] = a[i]
			i++
		} else {
			b[pos] = a[j]
			j++
		}
		pos++
	}
	for i := l; i <= r; i++ {
		a[i] = b[i]
	}
}

func main() {
	var n, d int
	fmt.Scanf("%v %v\n", &n, &d)

	for i := 0; i < n; i++ {
		var f, s int
		fmt.Scanf("%v %v\n", &f, &s)
		a[i] = pair{f, s}
	}
	mergeSort(0, n-1)
	ans, sum, l, r := 0, 0, 0, -1
	for r < n {
		r++
		sum += a[r].s
		// fmt.Printf("%v ->\n", r)
		for a[r].m-a[l].m >= d {
			// fmt.Printf("%v ", l)
			sum -= a[l].s
			l++
		}
		// fmt.Printf("\n")
		ans = Max(ans, sum)
	}

	fmt.Printf("%v", ans)
}