#include <bits/stdc++.h>
using namespace std;
int countBits(int mask) {
  int res = 0;
  while (mask) mask &= (mask - 1), ++res;
  return res;
}
string toString(long long n) {
  stringstream ss;
  ss << n;
  return ss.str();
}
long long toNumber(string s) {
  stringstream ss;
  long long n;
  ss << s;
  ss >> n;
  return n;
}
int main() {
  int n;
  string str;
  cin >> n;
  cin >> str;
  if (n % 2 == 1) cout << str[0], str = str.substr(1);
  for (int i = (int)(0), _m = (int)(str.size()); i < _m; ++i) {
    if (i != 0 && i % 2 == 0) cout << '-';
    cout << str[i];
  }
  cout << endl;
}
