#include<cstdio>
#include<set>
#include<algorithm>
using namespace std;
int n,x,l,nr,t;
long long s;
struct oita
{
    int x,ct;
}v[100005];
bool cmp(oita a,oita b)
{
    return(a.x<b.x);
}
void citire()
{
    scanf("%d%d%d",&n,&x,&l);
    for(int i=1;i<=n;i++)
        scanf("%d%d",&v[i].x,&v[i].ct);
}
struct comp
{
    bool operator()(const oita &a,const oita &b)
    {
        return(a.ct>b.ct);
    }
};
multiset<oita,comp>q;
int main()
{
    freopen("lupu.in","r",stdin);
    freopen("lupu.out","w",stdout);

    citire();
    oita z;
    sort(v+1,v+n+1,cmp);
    int i=1;nr=1;
    while(i<=n && v[i].x<=x)
    {
        t=(v[i].x+1)/l;
        while(i<=n && (v[i].x+1)/l==t && v[i].x<=x)
        {
            z.x=v[i].x;
            z.ct=v[i].ct;
            q.insert(z);
            i++;
        }
        s+=(*q.begin()).ct;
        z.x=(*q.begin()).x;
        z.ct=(*q.begin()).ct;
        q.erase(q.find(z));
        nr++;
    }
    printf("%d\n",s);

}