#include <bits/stdc++.h>
using namespace std;
const int dim=1e5+5;
int n,dmax,l,len,sol;
struct oaie{
    int dist,lana;
}a[dim];
bool cmp(oaie x, oaie y){
    if(x.lana==y.lana){
        return x.dist<y.dist;
    }
    return x.lana>y.lana;
}
signed main(){
    ifstream f("lupu.in");
    ofstream g("lupu.out");
    f>>n>>dmax>>l;
    for(int i=1;i<=n;i++){
        int dist,lana;
        f>>dist>>lana;
        if(dist<=dmax){
            a[++len]={dist,lana};
        }
    }
    sort(a+1,a+len+1,cmp);
    int pas=0;
    for(int i=1;i<=len;i++){
        if(a[i].dist+pas<=dmax){
            sol+=a[i].lana;
            pas+=l;
        }
    }
    g<<sol;
    return 0;
}