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

#define MAXN 1000010

int A[MAXN],DP[MAXN];
int i,st;
int D,N,K;

int main() {
	freopen("zombie.in","r",stdin);
	freopen("zombie.out","w",stdout);
	
	scanf("%d %d %d",&D,&N,&K);
	
	for(i=1;i<=N;i++)
		scanf("%d",&A[i]);
	
	st=1; DP[1]=1;
	for(i=2;i<=N;i++) {
		while(A[i]-A[st]+1>D)
			st++;
		DP[i]=min(DP[i-1]+1,DP[st-1]+K);
	}
	printf("%d",DP[N]);
}