#include<iostream>
#include<algorithm>
#include<cmath>
using namespace std;
int main() {
    int cnt=0;
  string s,t="";
  cin >> s;
  for(int i=s.size()-1; i>=0; i++) {
      cnt++;
      if(cnt==3) {
          t+=",";
          cnt=0;
      }
      t+=s[i];
  }
  reverse(t.begin(),t.end());
  cout << t << endl;
}