#include <fstream>
#include <queue>
#include <algorithm>

using namespace std;

pair<int,int> v[100001];
priority_queue<int> q;
long long n, x, l, s, i, u, d;

ifstream cin ("lupu.in");
ofstream cout ("lupu.out");

int main ()
{
    cin >> n >> x >> l;

    for(int i = 0 ; i < n ; i++)
        cin >> v[i].first >> v[i].second;

    sort(v, v + n);
    u = x % l;
    d = 0;

    for(i = u ; i <= x ; i += l)
    {
        for( ; d < n && v[d].first <= i ; ++d) q.push(v[d].second);
        if(!q.empty())
        {
            s += q.top();
            q.pop();
        }

    }

    cout << s << '\n';

    return 0;
}