#include<fstream>
#include<algorithm>
using namespace std;
ifstream fin("lupu.in");
ofstream fout("lupu.out");
struct abc
{
    int d,a;
};
abc v[100002];
int cmp(abc x, abc y)
{
    if(x.a==y.a)
        return x.d>y.d;
    return x.a>y.a;
}
int main()
{
    long long int s=0,d=0;
    int n,x,l;
    fin>>n>>x>>l;
    for(int i=0;i<n;i++)
    {
        fin>>v[i].d>>v[i].a;
    }
    sort(v,v+n,cmp);
    for(int i=0;i<n;i++)
    {
        if(v[i].d+d<=x)
        {
            s+=v[i].a;
            d+=l;
        }
        //fout<<v[i].d<<' '<<v[i].a<<' '<<d<<'\n';
    }
    fout<<s;
}