#include <fstream>
#include <algorithm>
#include <vector>
using namespace std;
ifstream cin("lupu.in");
ofstream cout("lupu.out");
vector<pair<int,int>>v;
bool comparator(pair<int,int>a,pair<int,int>b){
    if(a.first!=b.first){
    return a.second>b.second;
    }
    return a.first>b.first;
}
int main(){
    int n,x,l,rasp=0,d=0;
    cin>>n>>x>>l;
    v.resize(n+1);
    for(int i=1;i<=n;i++){
        cin>>v[i].first>>v[i].second;
    }
    sort(v.begin()+1,v.end(),comparator);

    for(int i=1;i<=n;i++){
       if(d+v[i].first>x){
        continue;
       }
        rasp+=v[i].second;
        d+=l;
    }
    cout<<rasp<<'\n';
}