https://pintia.cn/problem-sets/994805260223102976/problems/994805267416334336
#include <iostream>
#include <algorithm>
using namespace std;
int main(){
int N, num, h[10000] = {0}, cnt = 0, fri[10000] = {0}, sub = 0;
cin >> N;
for(int i = 0; i < N; i++){
cin >> num;
int sum = 0;
while(num){
sum += num % 10;
num /= 10;
}
if(!h[sum]){
cnt++;
fri[sub++] = sum;
h[sum]++;
}
}
sort(fri, fri + sub);
cout << cnt << endl << fri[0];
for(int i = 1; i < sub; ++i)
cout << " " << fri[i];
return 0;
}