#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
#define ma 50001
int n,i,k,j,r;
int V[ma],A[ma],REZ[ma];
int x;

ifstream f("economie.in");
ofstream g("economie.out");

int main()
{
	f>>n;
	for (i=1;i<=n;i++)
		f>>A[i];
	sort(A+1,A+n+1);
	r=0;
	V[0]=1;
	for (i=1;i<=n;i++)
	{
		if (!V[A[i]])
		{
			r++;
			REZ[r]=A[i];
			for (j=A[i];j<=A[n];j++)
				if (V[j-A[i]])
					V[j]=1;
		}
	}
	g<<r<<endl;
	for (i=1;i<=r;i++)
		g<<REZ[i]<<endl;
	f.close();
	g.close();
	return 0;
}