#include <fstream>
#include <algorithm>
#define dim 100003
#define x first
#define y second
using namespace std;

ifstream fin("lupu.in");
ofstream fout("lupu.out");
pair <int,int> v[dim];
int h[dim],n,i,j,X,L,a[dim],pp,nr,sol;
void insert(int x){
    a[++nr]=x;
    int c=nr,p=c/2;
    while(p>=1 && a[p]<a[c]){
        swap(a[p],a[c]);
        c=p;
        p/=2;
    }
}
void down(int k){
    a[k]=a[nr--];
    int p=k,c=2*p;
    while(c<=n){
        if(c+1<=n && a[c+1]<a[c])
            c++;
        if(a[p]<a[c]){
            swap(a[c],a[p]);
            p=c;
            c*=2;
        }
        else
            break;
    }
}
int main(){
    fin>>n>>X>>L;
    for(i=1;i<=n;i++)
        fin>>v[i].x>>v[i].y;
    sort(v+1,v+n+1);
    for(i=1;i<=n && v[i].x<=X;++pp){
        while(i<=n && v[i].x<=pp*L)
            insert(v[i].y),i++;
        if(nr)
            sol+=a[1],down(1);
    }
    fout<<sol;
    fin.close();fout.close();
    return 0;
}