# include <fstream>
# include <algorithm>
# include <set>
# define DIM 100010
# define INF -(1<<31)
# define f first
# define s second
using namespace std;
ifstream fin("lupu.in");
ofstream fout("lupu.out");
multiset<int> heap;
multiset<int>::iterator it;
pair<int,int> v[DIM];
int n,x,l,i;
long long s,t,q;
int main () {
    heap.insert(INF);
    fin>>n>>x>>l;
    for(i=1;i<=n;i++)
        fin>>v[i].f>>v[i].s;
    sort(v+1,v+n+1);
    while(v[1].f+t+l<=x)
        t+=l;
    for(i=1;i<=n;i++)
        v[i].f+=t;
    i=1;
    while(t>=0){
        while(v[i].f-q<=x&&i<=n){
            heap.insert(-v[i].s);
            i++;
        }
        it=heap.begin();
        it++;
        if(it!=heap.end()){
            s+=-(*it);
            heap.erase(it);
        }
        q+=l;
        t-=l;
    }
    fout<<s<<"\n";
    return 0;
}