#include <fstream>
#include <algorithm>
using namespace std;
ifstream cin("tribute.in");
ofstream cout("tribute.out");
int v[50001],w[50001];
int main()
{
    int n,l,c,i,st,dr,sum=0;
    cin>>n>>l>>c;
    for(i=1;i<=n;i++)
        cin>>v[i]>>w[i];
    sort(v+1,v+n+1);
    sort(w+1,w+n+1);
    st=1;
    dr=n;
    while(v[dr]-v[st]>=l)
          {
              sum+=v[dr--]-v[st++]-l;
          }
    st=1;
    dr=n;
    while(w[dr]-w[st]>=c)
          {
              sum+=w[dr--]-w[st++]-c;
          }
    cout<<sum;
    return 0;
}