#include <bits/stdc++.h>
using namespace std;

int 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 + 1) % 3 == 0 && i + 1 < s.size()) {
            t += ",";
        }
    }
    cout << t << endl;
    return 0;
}