import java.util.*;
public class Q584A{
    public static void main(String args[]){
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int t =sc.nextInt();
        if(t==10)
            if(n==1)
                System.out.print(-1);
            else
                System.out.print(1);
        else
            System.out.print(t);
        for(int i =1;i<n;i++)
            System.out.print(0);
        System.out.println();
    }
}

