#include <iostream>
#include <string>
#include <algorithm>
using namespace std;

int main() {
    string s1,res;
    cin>>s1;
    reverse(s1.begin(),s1.end());
    int count=0;
    int len=s1.size();
    for(char c:s1){
        res+=c;
        count++;
        if(count%3==0&&count!=len){
            res+=',';
        }
    }
    reverse(res.begin(),res.end());
    cout<<res;
}