#include <fstream>
using namespace std;
ifstream f("zombie.in");
ofstream g("zombie.out");
int d,n,k,i,j;
int a[2000100];
int ckr,poz;
int main()
{
	f>>d>>n>>k;
	for(i=1;i<=n;i++)
    f>>a[i];
	i=1;
	while (i<=n)
    {
		poz=i;
		if (a[i+k]-a[poz]>d)
			i++,ckr++;
		else
		{
			while(a[i+k]-a[poz]<=d&&i<=n) 
				i++;
			ckr+=k;
		}
	}
	g<<ckr<<'\n';
	return 0;
}