#!/usr/bin/ruby
n,k=gets.split.map(&:to_i)
a=$<.map{|e|e.split.map(&:to_i)}
p ma=(0..10**9).bsearch{|e|
	tail=-k
	!!a.each{|t,d|
		if d>e
			if t-tail<k
				break
			else
				tail=t
			end
		end
	}
}
ng=[false]*n
tail=-k
0.upto(n-1){|i|
	if a[i][1]>ma
		tail=a[i][0]
	elsif a[i][0]-tail<k
		ng[i]=true
	end
}
tail=a[-1][0]+k
(n-1).downto(0){|i|
	if a[i][1]>ma
		tail=a[i][0]
	elsif tail-a[i][0]<k
		ng[i]=true
	end
}
s=0
n.times{|i|
	if a[i][1]>ma
		a[i][1]=0
	else
		s+=a[i][1]
		a[i][1]=0 if ng[i]
	end
}
dp=[0]
t=x=0
n.times{|i|
	t=[t,dp[x+=1]].max while a[i][0]-a[x][0]>=k
	dp[i+1]=[dp[i],t+a[i][1]].max
}
p s-dp[n]