#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pii pair<int, int>
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < n; ++i)
#define rep3(i, l, n) for (int i = l; i < n; ++i)
#define chmax(a, b) a = max(a, b)
#define chmin(a, b) a = min(a, b)
#define out(a) cout << a << endl
#define SZ(v) (int)v.size()
#define inf (int)(1e9+7)
int main() {
    string s; cin >> s;
    if (SZ(s) <= 3) {
        out(s);
        return 0;
    }
    string t;
    int cnt = 0;
    for (int i = SZ(s) - 1; i >= 0; --i) {
        t += s[i];
        cnt++;
        if (cnt % 3 == 0) t += ',';
    }
    reverse(all(t));
    if (t[0] == ',') t = t.substr(1, SZ(t) - 1);
    out(t);
}