Please, help me with this problem. I don't know why WA. here my program (JAVA):
import java.util.Scanner;

public class Solution implements Runnable{
    Scanner in;

    public void run(){
        try{
            in = new Scanner (System.in);
            int n1 = in.nextInt();
            int n = n1;
            if (n == 0){
                System.out.print(10);
            }
            else{
                if (n == 1){
                    System.out.print(n);
                }
                else{
                    int[]mass = new int [n1];

                    for (int i = 0; i < n1; i++){
                        mass[i] = 0;
                    }

                    int j = 0;//указатель массива  mass

                    for (int i = 9; i > 1; i--){
                        boolean f = true;
                        while (f){
                            if (n % i == 0){
                                n = n / i;
                                mass[j] = i;
                                j++;
                                //System.out.print(i + " ");
                            }
                            if (n % i != 0){
                                f = false;
                            }
                        }
                    }
                    if (n >= 11){
                        System.out.print(-1);
                    }
                    else{
                        for (int i = n1 - 1; i >= 0; i--){
                            if (mass[i] != 0){
                                System.out.print(mass[i]);
                            }
                        }
                    }
                }
                }




        }
        catch( Exception er){
            er.printStackTrace();
            System.exit(-1);
        }
    }


    public static void main(String[] args) {
        new Thread (new Solution()).start();

    }

}