#include<bits/stdc++.h>
#define rep(i, x) for(ll i = 0; i < x; i++)
#define rep2(i, x) for(ll i = 1; i <= x; i++)
#define all(a) (a).begin(),(a).end()
using ll = long long;
using ld = long double;
using namespace std;
signed main() {
    string s, t; cin >> s; ll cnt = 0;
	for (int i = s.size() - 1; i >= 0; i--) {
		if (i != s.size() -1 && cnt % 3 == 0) { t.push_back(','); }
		t.push_back(s[i]);
		cnt++;
	}
	reverse(all(t)); cout << t << endl;
	return 0;
}