```
//a[],b[]都是int
include[HTML_REMOVED]
include[HTML_REMOVED]
include[HTML_REMOVED]
using namespace std;
const int N = 1010;
int a[N],b[N],c[N];
int n, m,num=0;
int get_unique_count(int a[], int n)
{
for (int i = 0; i < n; i)
{
b[a[i]];
if (b[a[i]] == 1)
{
c[num] = a[i];
}
}
return num;
}
int main()
{
cin >> n;
for (int i = 0; i < n; i) cin >> a[i];
stable_sort(a, a + n);
cout << get_unique_count(a, n)<<endl;
for (int i = 0; i < num; i++)
cout << c[i] << ‘ ‘;
return 0;
}
//a[]是小写字母
include[HTML_REMOVED]
include[HTML_REMOVED]
include[HTML_REMOVED]
using namespace std;
const int N = 110;
char a[N],c[N];
int b[N];
int num = 0;
int get_unique_count(char a[], int n)
{
for (int i = 0; i < n; i)
{
b[a[i] - 97];
if (b[a[i] - 97] == 1) c[num++]=a[i];
}
return num;
}
int main()
{
cin >> a;
int n = strlen(a);
stable_sort(a, a + n);
cout << get_unique_count(a, n) << endl;
for (int i = 0; i < num; i++) cout << c[i] << ” “;
return 0;
}