#include <bits/stdc++.h>

using namespace std;
int n,s,m;
long long sum,dt;
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    freopen("lupu.in","r",stdin);
    freopen("lupu.out","w",stdout);
    cin>>n>>s>>m;
    vector<pair<int,int>> v(n);
    for(auto &x:v)cin>>x.first>>x.second;
    sort(v.begin(),v.end(),[](const pair<int,int>& a,const pair<int,int>& b){
    return a.second<b.second;
    });
    for(int i=n-1;i>=0;i--)
    {
        if(v[i].first+dt<=s)
        {
        sum=sum+v[i].second;
        dt=dt+m;
        }
    }
    cout<<sum;

    return 0;
}