#include <bits/stdc++.h>
#define Nmax 100001
using namespace std;
ifstream f("lupu.in");
ofstream g("lupu.out");
pair <int,int> v[Nmax];
inline bool cmp(const pair <int,int> &x, const pair <int,int> &y)
{
    if(x.second==y.second)
        return x.first<y.first;
    else return x.second>y.second;
}
int main()
{
    int n,x,l,i;
    f>>n>>x>>l;
    for(i=1;i<=n;i++)
        f>>v[i].first>>v[i].second;
    sort(v+1,v+n+1,cmp);
    long long ans=0,nr=0;
    for(i=1;i<=n;i++)
        if(1LL*x>=l*nr+v[i].first)
        {
            ans+=v[i].second;
            nr++;
        }
    g<<ans;

    return 0;
}