#include <fstream>
#define NMAx 1000100
#define min(a,b) ((a)<(b)?(a):(b))
using namespace std;

int N,D,K,V[NMAx],DP[NMAx];

int main() {
	
	int L,R;
	ifstream in("zombie.in");
	ofstream out("zombie.out");
	
	in>>D>>N>>K;
	
	for(L=R=1;R<=N;R++) {
		
		in>>V[R];
		
		while(V[R]-V[L]>D)
			L++;
		
		DP[R]=min(DP[R-1]+1,DP[L-1]+K);
		
		}
	
	out<<DP[N];
	
	in.close();
	out.close();
	
	return 0;
	
}