#include <fstream>
#include <set>
#include <algorithm>
#define nmax 100001


using namespace std;

ifstream f("lupu.in");
ofstream g("lupu.out");

struct oaie{
	int timp;
	int lana;
	bool operator<(const oaie& a)  {
		return this->timp<a.timp;
	}
};
int main(){
	int n, x, l, i, total=0, nr, k=0, a, b;
	multiset<int> mp;
	oaie oita[100003];	
	f>>n>>x>>l;
	for(i=1;i<=n;i++){
		f>>a>>b;
		if(a<=x){
			k++;
			oita[k].timp=(x-a)/l+1;
			oita[k].lana=b;
		}
	}	
	sort(oita+1,oita+k+1);
	int t=oita[k].timp;
	nr=k;
	for(i=t;i>=1;i--){
		while(nr>0 && oita[nr].timp==i){
			mp.insert(oita[nr].lana);
			nr--;
		}
		if(!mp.empty()){
			total+=*(mp.rbegin());
			mp.erase(--mp.end());
		}
	}
	g<<total<<" ";
  
}