#include<stdio.h>
#include<ctype.h>
#include<fstream>
using namespace std;

ifstream f("zombie.in");

#define MaxN 1000100

int N,D,K,A[MaxN];
int B[MaxN];

void citire(void)
{
	f >> D >> N >> K;
	for(int i=1;i<=N;i++)
		f >> A[i];
}

void zombie(void)
{
	int c = 0;
	for(int i=1;i<=N;i++)
	{
		B[i] = B[i-1]+1;
		while(A[c] <= B[i]-D) ++ c;
		if(B[i] > B[c-1]+K)
			B[i] = B[c-1] + K;
	}
}

int main()
{
	FILE *g = fopen("zombie.out","w");
	
	citire();
	zombie();
	fprintf(g,"%d ",B[N]);
	
	fclose(g);
	return 0;
}