#include <bits/stdc++.h>

using namespace std;
ifstream fin("lupu.in");     //strudel
ofstream fout("lupu.out");   //strudel
struct aaa{
    long long v,d;
};
aaa a[100010];
priority_queue<int> pq;
long long n,x,c,i,k,d,p,r,s,l;
bool cmp(aaa a,aaa b){
    return a.d<b.d;
}
int main()
{
    fin>>n>>x>>l;
    for(i=1;i<=n;i++) fin>>a[i].d>>a[i].v;
    sort(a+1,a+n+1,cmp);
    for(r=0;r*l<x+l;r++){
        while(p<n && a[p+1].d<=min(x,r*l)) pq.push(a[++p].v);
        if(!pq.empty()){
            // fout<<r<<" "<<pq.top()<<'\n';
            // if(a[pq.top()].v+2<=min(x,r*l))
            s+=pq.top(), pq.pop();
        }
    }
    fout<<s;
    return 0;
}