1120 Friend Numbers

#include <iostream>
#include <cstring>
#include <string>
#include <sstream>
#include <string>
#include <cstdio>
#include <cmath>
#include <algorithm>
#include <map>
#define maxn 10005
#define INF 0x3f3f3f3f
#define EPS 1e-6
#define pi acos(-1.0)
using namespace std;
typedef long long ll;
int n,x,sum;
int a[maxn],b[maxn],vis[maxn];
int main()
{
    scanf("%d",&n);
    for(int i=0;i<n;i++)
    {
        sum=0;
        scanf("%d",&x);
        while(x)
        {
            sum+=x%10;
            x=x/10;
        }
        a[i]=sum;
    }
    sort(a,a+n);
    int p=unique(a,a+n)-a;
    printf("%d\n",p);
    printf("%d",a[0]);
    for(int i=1;i<p;i++)
    {
        printf(" %d",a[i]);
    }
    
    printf("\n");
}