#include <fstream>
using namespace std;

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

const int N=1000005;
int v[N],c[N];

int main()
{
	int d,n,k,i,st,dr;
	in>>d>>n>>k;
	
	for(i=1;i<=n;i++)
		in>>v[i];
	
	st=dr=1;
	
	while(dr<=n)
	{
		while(v[dr]-v[st]>d)
			st++;
		
		if(c[st-1]+k<c[dr-1]+1)
			c[dr]=c[st-1]+k;
		else
			c[dr]=c[dr-1]+1;
		dr++;
	}
	
	out<<c[n];
	return 0;
}