#include <fstream>

using namespace std;

ifstream f("zombie.in");
ofstream g("zombie.out");

int d,n,k,t[1000001],z,cost,i,j;

int main () {
    f >> d >> n >> k;
    for (i=1;i<=n;i++) f >> t[i];
    i=1;
    while (i<=n) {
        z=0;j=i;
        while (j<=n+1 && t[j]<=t[i]+d-2) {
            j++;
            z++;
        }
        i=j;cost+=min(z,k);
    }
    g << cost << '\n';
    f.close();g.close();
    return 0;
}