#include <stdio.h>
int main()
{
	int a=1,c,i,j,n;
	scanf("%d",&n);
	int b[n];
	for (i=0; i<n; i++)
		scanf("%d",&b[i]);
	for (i=0; i<n; i++)
		for (j=0; j<n-i; j++)
			if (b[j] > b[j+1])
				{
					c = b[j+1];
					b[j+1] =b[j];
					b[j] = c;
				}
	for (i=0; i<n; i++)
	{
		for (j=i+1; j<n; j++)
			if(b[i]==b[j])
				b[j]=0;
	}
	for (i=0;i<n;i++)
	{
		if(b[i]!=0)
			a++;
		else
			continue;
	}
	printf("%d\n",a);
	for (i=0; i<=n; i++)
		if(b[i]!=0)
			if(i!=n)
				printf("%d ",b[i]);
			else
				printf("%d",b[i]);
		else
			continue;
return 0;
}

没什么经验，写的有点乱，麻烦了。