#include<time.h>

#include<stdlib.h>

int main(void)

{

int num = 0,count = 0,temp = 0,num1 = 0,count1 = 0,r = 0,num2 = 0;

int arr[1000] = {0};

scanf("%d",&count);

for(num = 0;num < count;num++)

{

scanf("%d",&r);

for(num1 = 0;num1 < num;num1++)

{

if(r == arr[num1])

{

break;

}

}

if(num1 == num)

{

arr[count1] = r;

count1++;

}

}

for(num = 0;num < count1 - 1;num++)

{

for(num1 = num +1;num1 < count1;num1++)

{

if(arr[num] > arr[num1])

{

temp = arr[num];

arr[num] = arr[num1];

arr[num1] = temp;

}

}

}

printf("%d\n",count1);

for(num = 0;num < count1;num++)

{

printf("%d ",arr[num]);

}

printf("\n");

return 0;

}