#include <bits/stdc++.h>

using namespace std;

ifstream fin("zombie.in");
ofstream fout("zombie.out");
const int NMAX = 1000005;
int v[NMAX];
int main()
{
    int n,d,k,x,s = 0,j;
    fin >> d >> n >> k;
    for(int i = 1; i <= n; i++)
        fin >> v[i];
    for(int i = 1; i <= n; i++){
        for(j = i + 1; v[j] - v[i] <= d && j <= n; j++);
        j--;
        if(j - i >= k){
            s += k;
            i = j;
        } else
            s++;
    }
    fout << s;
    return 0;
}