import java.util.*;
public class main{
    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);
        int n=scan.nextInt(),i=0,j=1;
        int[] a=new int[n];
        int[] b=new int[n];
        for(i=0;i<n;i++)
        {
            if(a[i]<=0)
            {
                System.out.println("Invalid input");
                Break;
            }
            else
            {
                a[i]=scan.nextInt();
            }
        }
        for(i=0;i<n;i++)
        {
            j*=a[i];
        }
        System.out.println(j);
    }
}