#include <algorithm>
#include <iostream>
#include <fstream>
using namespace std;
ifstream in("lupu.in");
ofstream out("lupu.out");
const int maxn = 100005;
pair <int, int> v[maxn];
int main()
{
    int n, x, l;
    in >> n >> x >> l;
    for(int i = 1; i <= n; i++)
        in >> v[i].second >> v[i].first;
    sort(v + 1, v + n + 1);
    reverse(v + 1, v + n + 1);
    int lg = 0;
    int lana = 0;
    for(int i = 1; i <= n; i++)
    {
        if(v[i].second + lg <= x)
        {
            lana = lana + v[i].first;
            lg += l;
        }
    }
    out << lana << "\n";
    return 0;
}