https://pintia.cn/problem-sets/994805342720868352/problems/994805352925609984
#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10;
int cnt[N],n,x;
void solve(int x)
{
int sum=0;
while(x) sum+=x%10,x/=10;
cnt[sum]++;
}
int main(void)
{
cin>>n;
for(int i=0;i<n;i++) cin>>x,solve(x);
vector<int>ve;
for(int i=0;i<N;i++) if(cnt[i]) ve.push_back(i);
cout<<ve.size()<<endl;
for(int i=0;i<ve.size();i++)
{
if(i) cout<<" ";
cout<<ve[i];
}
return 0;
}