#include <bits/stdc++.h>
using namespace std;
string A[102400] = {};
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  int a;
  while (cin >> a) {
    string ans = "1";
    int zer = 0;
    int s = -1;
    for (int i = 0; i < a; i++) {
      cin >> A[i];
      if (A[i] == "0") {
        zer = 1;
      }
      if (s == -1) {
        int sum = 0;
        for (int j = 0; j < A[i].size(); j++) {
          if (A[i][j] == '1') {
            sum++;
          }
          if (sum >= 2 || (A[i][j] != '1' && A[i][j] != '0')) {
            ans = A[i];
            s = i;
            break;
          }
        }
      }
    }
    if (zer == 1) {
      cout << 0 << endl;
      continue;
    }
    for (int i = 0; i < a; i++) {
      if (i == s) {
        continue;
      }
      for (int j = 0; j < A[i].size(); j++) {
        if (A[i][j] == '0') ans += '0';
      }
    }
    cout << ans << '\n';
  }
  return 0;
}
