#include <fstream>
#include <algorithm>
using namespace std;

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

int v[100005], dp[100005];
int a, b, i, j, n, m, d, k;
//d distanta, k chakra pentru vraja laser

int main(){
	f>>d>>n>>k;
	for (i=1; i<=n; i++) f>>v[i];
	sort (v+1, v+n+1);
	
	dp[1]=1;
	a=1;
	for (i=2; i<=n; i++){
		while (v[i]-v[a]>d) a++;
		dp[i]=min (dp[i-1]+1, dp[a-1]+k);
	}
	g<<dp[n];
}