#include <fstream>
#include <algorithm>
#define dist second
#define wool first

using namespace std;

ifstream f("lupu.in");
ofstream g("lupu.out");

const int nmax = 100005;
int prey, scared, n, sumi;
pair<int, int> A[nmax];

int main()
{
    f >> n >> prey >> scared;

    for(int i = 1; i <= n; i ++)
        f >> A[i].dist >> A[i].wool;

    sort(A + 1, A + n + 1);

    int run = 0;
    for(int i = n; i >= 1; i --)
        if(A[i].dist + run <= prey)
        {
            sumi += A[i].wool;
            run += scared;
        }

    g << sumi;
    return 0;
}