#include<fstream>
using namespace std;
ifstream f("zombie.in");
ofstream g("zombie.out");
int n,d,k,a[1000005],i,j,sum;
int main()
{
    f>>d>>n>>k;
    for(i=1;i<=n;i++)
      f>>a[i];
    for(i=1;i<n;i=j)
    {
        for(j=i;j<=n&&a[j]-a[i]<d;j++);
        sum+=min(j-i,k);
        //g<<i<<" "<<j<<"\n";
    }
    g<<sum;
    return 0;
}