#include<stdio.h>
#include<algorithm>
using namespace std;
FILE*f=fopen("economie.in","r");
FILE*g=fopen("economie.out","w");
int n,ok,i,j,ok2;
int v[1010];
int m[1010];
int main () {
	fscanf(f,"%d",&n);
	for(i=1;i<=n;i++)
		fscanf(f,"%d",&v[i]);
	sort(v+1,v+n+1);
	m[0]=1;
	ok=1;
	for(i=1;i<=n&&ok!=0;i++){
		if(m[v[i]]==0){
			m[v[i]]=1;
			for(j=0;j<=v[n]+1;j++){
				if(m[j]==1&&j+v[i]<=v[n]+1)
					m[j+v[i]]=1;
			}
			ok2=0;
			for(j=1;j<=n;j++){
				if(m[v[j]]==0){
					ok2=1;
					break;
				}
			}
			if(ok2==0)
				ok=0;
		}
	}
	fprintf(g,"%d\n",i-1);
	for(j=1;j<=i-1;j++)
		fprintf(g,"%d ",v[j]);
	fclose(f);
	fclose(g);
	return 0;
}