package a;public class A {public static void main(String[] args) {int a[]={1,4,9,9};fun(a,0);}? ? ?public static void ?fun(int a[],int k){? ??if(isOk(a)){? ??for(int i=0;i<a.length;i++){? ??System.out.print(a[i]);? ??}? ??System.out.println();? ??}? ??for(int i=k;i<a.length;i++){? {int temp =a[i];? a[i]=a[k];? a[k]=temp;}? fun(a,k+1);? {int temp =a[i];? a[i]=a[k];? a[k]=temp;}? }? ? ?}? ? ?public static boolean isOk(int a[]){? ??int m= a[0]*1000+a[1]*100+a[2]*10+a[3];? ??for(int i=2;i<Math.sqrt(m);i++){? ??if(m%i==0){? ??return false;? ??}? ??}? ??int a1=0;int a2=0;int a3=0;? ??for(int i=0;i<a.length;i++){? ??if(a[i]==1){? ??a1++;? ??} if(a[i]==4){? ??a2++;? ??} if(a[i]==9){? ??a3++;? ??}? ??}? ??if(a1!=1||a2!=1||a3!=2){? ??return false;? ??}? ??return true;? ? ?}}