#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string a;
  cin >> n >> a;
  for (int i = 0; i < n; i += 2) {
    int c = max(n - i, 2);
    if (c > 3) c = 2;
    cout << a.substr(i, c);
    if (c == 3) break;
    if (i + 2 < n) cout << "-";
  }
  cout << endl;
}
