#include <bits/stdc++.h>

using namespace std;

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

priority_queue <long long> pq;
vector <vector <long long>> v;

long long n,x,l,a,b,maxim,s;
int main()
{
    f>>n>>x>>l;
    for(int i=1;i<=n;i++)
    {
        f>>a>>b;
        if(a<=x)
        {
            a=(x-a)/l;
            if(a>maxim)
                maxim=a;
            v.resize(maxim+1);
            v[a].push_back(b);
        }
    }
    for(int i=maxim;i>=0;i--)
    {
        for(int j=0;j<v[i].size();j++)
            pq.push(v[i][j]);
        if(pq.size()!=0)
        {
            s=s+pq.top();
            pq.pop();
        }
    }
    g<<s;
    return 0;
}