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

int main() {
    string s;
    cin >> s;
    const int n = s.length();
    reverse(s.begin(), s.end());
    
    string t = "";
    for (int i = 0; i < n; i++) {
        t += s[i];
        if (i % 3 == 2 and i + 1 < n) t += ",";
    }
    reverse(t.begin(), t.end());
    cout << t << endl;
    return 0;
}