#include<bits/stdc++.h>
using namespace std;

int i,j,a[1000005],n,k,d;
long long rs;

int main()
{
  ifstream cin("zombie.in");
  ofstream cout("zombie.out");

  ios_base::sync_with_stdio(0);

  cin>>d>>n>>k;
  for(i=1;i<=n;++i) cin>>a[i];

  for(j=i=1;i<=n;++i)
  {
    while(j<n && a[j+1]-a[i]<=d) ++j;
    if(j-i>=k) rs+=k,i=j;
    else ++rs;
  }

  cout<<rs<<'\n';

 return 0;
}