#include <bits/stdc++.h>
using namespace std;
bool solve(string s) {
  int cnt = 0;
  bool t = true;
  for (int i = 0; i < s.size(); ++i) {
    if (s[i] == '1') cnt++;
    if (s[i] != '1' && s[i] != '0') t = false;
  }
  return (t == true && cnt == 1);
}
int main() {
  long long n;
  cin >> n;
  string cnt = "";
  int idx = -1;
  bool t = false;
  string arr[n];
  for (int i = 0; i < n; ++i) {
    cin >> arr[i];
    string s = arr[i];
    if (s[0] == '0') t = true;
    if (solve(s) == false) cnt = s, idx = i;
  }
  if (t == true) {
    cout << 0;
    return 0;
  }
  cout << cnt;
  if (idx == -1) cout << 1;
  for (int i = 0; i < n; ++i) {
    if (i == idx) continue;
    for (int j = 1; j < arr[i].size(); ++j) cout << arr[i][j];
  }
  return 0;
}
