学步园

#include<algorithm>
#include<iostream>
#include<cstdio>
using namespace std;
inline int read(){
    int x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
int n,num[101],tot;
int main(){
	n=read();
	for(int i=1;i<=n;++i)
		num[i]=read();
	sort(num+1,num+n+1);
    tot=unique(num+1,num+n+1)-num-1;
    printf("%d\n",tot);
	for(int i=1;i<=tot;++i)
		cout<<num[i]<<" ";
    return 0;
}