#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  string s;
  cin >> n >> s;
  int k = n / 2 - 1;
  for (int i = 0, j = 0; i < n; ++i) {
    cout << s[i];
    j++;
    if (j % 2 == 0 && k--) cout << '-';
  }
  return 0;
}
