#include<fstream>
using namespace std;
int main()
{
    ifstream q("zombie.in");
    ifstream sf("zombie.in");
    ofstream w("zombie.out");
    int dt,poz,zsfarsit,zinceput,d,n,k,costS=0,luate=0,ps=0,pi=0,pozi=1;
    bool pending=false;
    sf>>d>>n>>k;
    if(k==d)
    {
        w<<n;
        return 0;
    }
    poz=1;
    q>>d>>n>>k;
    q>>zinceput;
    sf>>zsfarsit;
    while(poz<=n)
    {
        dt=zsfarsit-zinceput+1;
        if(dt<d)
         {if(poz-pozi+1>k)
        {
            pending=true;
            ps=poz;
            pi=pozi;
        }}
        else{
          if(pending)
          {
              luate=luate+ps-pi+1;
              costS=costS+k;
              pending=false;
              /*while(pozi<poz-1){
               q>>zinceput;
               pozi++;
               }*/
          }
          q>>zinceput;
          pozi++;
          }
        poz++;
        if(poz<=n){
        sf>>zsfarsit;}
    }
    if(pending)
          {
              luate=luate+ps-pi+1;
              costS=costS+k;
              pending=false;
          }
    w<< costS+n-luate;
    return 0;
}