代码如下：

#include<iostream>
#include<algorithm>
using namespace std;
struct non{
	int d;
	int m;
} a[300005];
int cmp(non a,non b){
	if(a.d<b.d)
		return 1;
	return 0;
}
int ff(int ma){
	if(ma>=0)
		return ma;
	return 0;
}
int main()
{
	int n,k;
	cin>>n>>k;
	for(int i=1; i<=n; i++)
		cin>>a[i].d>>a[i].m;
	sort(a+1,a+1+n,cmp);
	int sum=0;
	for(int i=1; i<=n; i++){
		if(a[i].m-k<=0)
			sum+=k;
		else if(a[i+1].d!=a[i].d) 
			sum+=ff(k*2-a[i].m);
		else sum+=k;
		cout<<sum;
	}
	cout<<sum;
	return 0;
}