using namespace std;
#include<iostream>
#include<fstream>
#include<queue>
#define Nmax 100005
#define D first
#define A second
ofstream fout("lupu.out");
priority_queue<int> q;
pair<int,int> v[Nmax];
int N,X,L;
unsigned long long sum;
void solve()
{int i,lim=1;
    for(i=X%L;i<=X;i+=L)
    {
         while(lim<=N&&v[lim].D<=i)
           {q.push(v[lim].A);
           lim++;
           }
         sum+=q.top();
         q.pop();

    }
    fout<<sum<<"\n";
}
void cit()
{int i;
    ifstream fin("lupu.in");
    fin>>N>>X>>L;
    for(i=1;i<=N;i++)
     {fin>>v[i].D>>v[i].A;
     }
    sort(v+1,v+N+1);


}

int main()
{

    cit();
    solve();
    fout.close();
    return 0;
}