#include <cstdio>
#include <fstream>
#include <queue>
#include <algorithm>

using namespace std;

#define f first
#define s second

pair<int,int> v[100001];
priority_queue<int> q;
long long n,x,l,s,i,u,d;

int main ()
{
	
	ifstream f ("lupu.in");
	freopen ("lupu.out","w",stdout);
	f>>n>>x>>l;
	for(i=0;i<n;++i)
		f>>v[i].f>>v[i].s;
	sort(v,v+n),u=x%l,d=0;
	for(i=u;i<=x;i+=l){
		for(;d<n&&v[d].f<=i;++d)q.push(v[d].s);
		if(q.size()){
			s+=q.top();
			q.pop();
			}
		}
	printf("%lld",s);
	
	return 0;}