#include<fstream>

#define NMAX 1000005

using namespace std;

ifstream fin("zombie.in");
ofstream fout("zombie.out");

int n,k,d,DP[NMAX],v[NMAX];

int main()
{
	fin>>d>>n>>k;
	for(int i=1;i<=n;i++)
		fin>>v[i];
	DP[1]=1;
	for(int i=2,ind=0;i<=n;i++)
	{
		for(;v[i]-v[ind+1]>=d;ind++);
		DP[i]=min(DP[i-1]+1,DP[ind]+k);
	}
	fout<<DP[n];
	return 0;
}