#include<cstdio>
#define NMAX 1000
using namespace std;
int a[NMAX][NMAX], x[NMAX], n, sol[NMAX];

int main()
{
    freopen("scmax.in", "r", stdin);
    freopen("scmax.out","w", stdout);

    scanf("%d", &n);
    unsigned int el;
    x[0] = 1;
    for(int i = 1; i <= n; ++i)
    {
        bool ok = true;
        scanf("%d", &el);
        for(int j = 1; j < x[0]; ++j)
        {
            if(el == x[j])
            {
                ok = false;
                break;
            }
        }
        if(ok == true)
        {
            x[x[0]] = el;
            ++x[0];
        }
    }
    n= n - (n - (x[0] - 1));

    for(int i = 1; i <= n; ++i)
        for(int j = 1 ; j <= n; ++j)
            if(x[i] <= x[j] && i != j)
                a[i][j] = a[i - 1][j - 1] + 1;
            else
                a[i][j] = (a[i - 1][j] > a[i][j - 1] ? a[i - 1][j] : a[i][j - 1]);
    sol[0] = 1;
    for(int i = n, j = n; i > 0 && j > 0;)
    {
        if(x[i] <= x[j] && a[i][j] != 0)
        {
            sol[sol[0]] = x[i];
            sol[0]++;
            i--;
            j--;
        }
        else
        if(a[i - 1][j] == a[i][j - 1])
            i--,j--;
        else
        if(a[i - 1][j] < a[i][j - 1])
            j--;
        else
            i--;
    }

    printf("%d\n", sol[0] - 1);

    for(int i = sol[0] - 1; i > 0; --i)
        printf("%d ", sol[i]);
    printf("\n");

    return 0;

}