#include <fstream>
#include <deque>
using namespace std;
deque <int> v;
int main()
{ int d,n,k,i,nr,sol=0,x;
    ifstream f("zombie.in");
    ofstream g("zombie.out");
    f>>d>>n>>k;
    for (i=1;i<=n;++i) {
        f>>x;
        nr=0;
        while (!v.empty() && x-v.front()>=d) {
            ++nr;
            v.pop_front();
        }
        sol+=min(nr,k);
        v.push_back(x);
    }
      nr=v.size();
      sol+=min(nr,k);
      g<<sol;
    return 0;
}