C++ :

#include <cstdlib>
#include <cstdio>
#include <algorithm>
int array[103];
int out[103];
using namespace std;
int main()
{
    int n;
    scanf("%d",&n);
    int n_n=n;
    for(int i=1;i<=n;i++)
    {
        scanf("%d",&array[i]);
    }
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++)
        {
            if(array[i]==array[j]&&i!=j)
            {
                n_n--;
                array[i]=-1;
            }
        }
    }
    printf("%d\n",n_n);
    int c=1;
    for(int i=1;i<=n;i++)
    {
        if(array[i]!=-1)
        {
            out[c]=array[i];
            c++;
        }
    }
    sort(out+1,out+n_n+1);
    for(int i=1;i<=n_n;i++)
    {
        printf("%d ",out[i]);
    }
    //system("pause");
    return 0;
}

Pascal :

program ex;
var n,x,i,s:integer;
    a:array[1..1000]of integer;

begin
    readln(n);
    for i:=1 to 1000 do
     a[i]:=0;
    for i:=1 to n do
     begin
     read(x);
     a[x]:=1;
     end;
    s:=0;
    for i:=1 to 1000 do
      s:=s+a[i];
    writeln(s);
    for i:=1 to 1000 do
      if a[i]>0 then write(i,' ');
end.

Python :

# coding=utf-8
#明明的随机数
n=int(input())
ls=list(map(int,input().split()))
ls.sort()
ls2=[ls[0]]
j=0
for i in range(1,len(ls)):
	if ls2[j]!=ls[i]:
		ls2.append(ls[i])
		j=j+1
	else:
		continue
print(len(ls2))
for i in range(len(ls2)):
	print(ls2[i],end='')
	if i<len(ls2)-1:
		print(' ',end='')