#include <stdio.h>
int main ()
{
    int N,cnt =0;
    int range[101],R[1000+1];
    scanf ("%d",&N);
    for (int i=0;i<=1001;i++)
    {
        R[i]=0;
    }
    for (int i=0;i<N;i++)
    {
        scanf ("%d ",&range[i]);
    }
    for (int i=0;i<=1001;i++)
    {
        for (int j=0;j<N;j++){
            if(i==range[j]) R[i]=1;
        }
    }
    for (int i=0;i<=1001;i++)
    {
        if (R[i]==1) cnt++;
    }
    printf("%d",cnt);
    for (int i=0;i<=1001;i++)
    {
        if (R[i]==1) printf("%d ",i);
    }
    return 0;
}