#include <bits/stdc++.h>
using namespace std;
const long long N = 3e5 + 5;
void solve() {
  long long n;
  cin >> n;
  string s;
  cin >> s;
  if (n % 2 == 0) {
    for (int i = 0; i < n; i++) {
      if ((i != 0 && i % 2 == 0)) cout << "-";
      cout << s[i];
    }
    cout << endl;
  } else if (n % 2 == 1) {
    cout << s[0];
    for (int i = 1; i < n; i++) {
      if ((i != 1 && i % 2 == 1)) cout << '-';
      cout << s[i];
    }
    cout << endl;
  }
  return;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  ;
  solve();
  return 0;
}
