#include <stdio.h>
#include <stdlib.h>
#include <string.h>



int remove_duplicates(int arr[], int n) {
    // TODO: implement this function
    return 0;
}


int main(void) {
    int n;
    if (scanf("%d", &n) != 1) { n = 0; }
    int arr[1000];
    for (int i = 0; i < n; i++) { scanf("%d", &arr[i]); }
    int count = remove_duplicates(arr, n);
    printf("%d\n", count);
    for (int i = 0; i < count; i++) {
        printf("%d", arr[i]);
        if (i < count - 1) { printf(" "); }
    }
    printf("\n");
    return 0;
}