#include <bits/stdc++.h> using namespace std; signed main(){ string s;cin>>s; reverse(s.begin(),s.end()); string t; for(int i=0;i<s.size();i++){ t+=s[i]; if(i%3==0&&i+1!=s.size())t+=','; } reverse(t.begin(),t.end()); cout<<t<<endl; }