#include <iostream>
#include <cstdio>
#include <algorithm>
#define nmax 100005
using namespace std;
int n,x,len,sum,m;
struct Coord{
    int d,b;
};
Coord a[nmax];
inline  bool cmp(const Coord A,const Coord B){
    if(A.d == B.d) return A.b > B.b;
 return A.d > B.d;
}
int main(){
    int i;
    freopen("lupu.in","r",stdin);
    freopen("lupu.out","w",stdout);
    scanf("%d%d%d",&n,&x,&len);
    for(i=1;i<=n;i++){
        scanf("%d%d",&a[i].d,&a[i].b);
    }
    sort(a+1,a+n+1,cmp);
//    for(i=1;i<=n;i++)
//        cout<<a[i].d<<' '<<a[i].b<<'\n';
      for(i=1;i<=n;i++){
        if(a[i].d +len*m<= x && a[i+1].d+len*m<= x && a[i].b > a[i+1].b){sum+=a[i].b;m++;}
        else if(a[i].d + len +len*m> x && a[i+1].d+len+len*m<= x && a[i].d <= x){sum+=a[i].b;m++;}
       // cout<<sum<<' ';
      }
      cout<<sum;
    return 0;
}