#include <iostream>
#include <string>

using namespace std;

int main()
{

  int n;
  cin >> n;
  int arr[n];
    for ( int i = 0 ; i < n ; i++ )
    {
      cin >> arr[i];
    }
    for ( int j = 0 ; j < n ; j++)
    {
      for (int i = 0 ; i < n-1 ; i++)
      {
        if ( arr[i] == 0 )
        {
          swap(arr[i] , arr[i+1]);
        }
      }
    }
    for ( int i = 0 ; i < n ; i++)
    {
      cout << arr[i];
    } 
    return 0;
}