#define _USE_MATH_DEFINES

#include <iostream>	//cin, cout
#include <vector>	//vector
#include <algorithm> //sort,min,max,count
#include <string>	//string,getline, to_string
#include <ios>		//fixed
#include <iomanip>	//setprecision
#include <utility> //swap, pair
#include <cstdlib>	//abs(int)
#include <cmath>	//sqrt,ceil,M_PI, pow, sin
#include <sstream>	//stringstream,getline
#include <numeric>	//gcd, accumlate
#include <deque>	//deque
#include <random>	//randam_device
#include <limits>	//numeric_limits

using namespace std;
constexpr long long int D_MOD = 1000000007;

int main() {

	string str;
	cin >> str;

	string S;
	int cnt = 0;

	for (int i = str.length() - 1; i >= 0; i--) {
		S.push_back(str[i]);
		cnt++;
		if (cnt == 3) {
			S.push_back(',');
			cnt = 0;
		}
	}

	if (S.back() == ',') {
		S.pop_back();
	}

	for (int i = S.length() - 1; i >= 0; i--) {
		cout << S[i];
	}
	cout << endl;

	return 0;

}