#include <iostream>
#include <vector>
#include <string>
#include <cmath>
#include <algorithm>
#include <utility>
#include <queue>
#include <set>
#include <map>
#include <deque>
#include <iomanip>
#include <cstdio>
#include <stack>
#include <numeric>

using namespace std;
typedef  long long ll;
typedef pair<int,int> PII;
typedef vector<int> VI;
typedef vector<VI> VVI;
#define  MP make_pair
#define  PB push_back
#define inf  1000000007
#define rep(i,n) for(int i=0;i<(int)(n);++i)


int main(){
    string s;
    cin >> s;
    int n = s.size();
    reverse(s.begin(),s.end());
    string t;
    for(int i=0;i<n;i++){
        if(i%3==0&&i!=0){
            t.push_back(',');
        }
        t.push_back(s[i]);
    }
    reverse(t.begin(),t.end());
    cout << t << endl;
    return 0;
}