#include <fstream>
#include <vector>
#include <algorithm>
#include <set>

using namespace std;

ifstream cin("lupu.in");
ofstream cout("lupu.out");

#define int long long
vector < int > dp;
vector < pair < int , int > > v;
set < int > s;

signed main()
{
    int n,x,l,ans=0;
    cin>>n>>x>>l;
    dp.resize(n+1);
    v.resize(n+1);
    for(int i=1;i<=n;i++)
        cin>>v[i].first>>v[i].second;
    sort(v.begin()+1,v.end());
    int best=0,nextl=0;
    for(int i=1;i<=n;i++)
    {
        if(v[i].first>x || i==n){
            if(s.size())
            {
                best=*s.rbegin();
                ans+=best;
            }
            break;
        }
        while(s.size() && v[i].first>nextl)
        {
            best=*s.rbegin();
            nextl=nextl+l;
            ans+=best;
            s.erase(best);
        }
        s.insert(v[i].second);
        //cout<<i<<" "<<ans<<'\n';
    }
    cout<<ans;
    return 0;
}