#include <iostream>
#include <fstream>
#include <algorithm>
#include <queue>
using namespace std;
ifstream in("lupu.in");
ofstream out("lupu.out");
 
const int N=1+1e6;
struct Oaie{
    int d,l;
    Oaie(){}
    Oaie(int a ,int b){
        d=a;
        l=b;
    }
};
 
priority_queue<int> h;
Oaie o[N];
int n,x,f,k;
bool cmp(Oaie a, Oaie b){
    return a.d<b.d;
}
int main()
{
    int a,b;
    in>>n>>x>>f;
    for(int i=1 ; i<=n ; i++){
        in>>a>>b;
        if(a<=x){
            o[++k]=Oaie(a,b);
        }
    }
    sort(&o[1], &o[k+1], cmp);
    for(int i=1 ; i<=k ; i++){
        if( o[i].d + h.size()*f <=x){
            h.push(-o[i].l);
        }else{
            if(o[i].l>h.top()){
                h.pop();
                h.push(-o[i].l);
            }
        }
    }
    int s=0;
    while(!h.empty()){
        s-=h.top();
        h.pop();
    }
    out<<s;
 
    return 0;
}