public static void main ( String [] args ) {

	int sum=0, limit =28123;
	int[] delDuplication=new int[limit+1];
	int[] abNum=new int[28123];
	int counter=0;

	for ( int i=0; i<delDuplication.length; i++ ) {
	    delDuplication[i] = 0;
	}
	     

	for ( int i=12; i<limit; i++ ) {
	    if ( isAbundant(i)==true ) {					
		abNum[counter]=i;
		counter++;
	    }
	}
	
	for ( int i=0; i<counter; i++ ) {
	    for ( int j=0; j<=i; j++ ) {
		// use serial number of array to avoid duplication
		if ( abNum[i]+abNum[j]<=limit ) {
		    delDuplication[abNum[i]+abNum[j]]=1;
		}
	    }
	}
            
	for(int i=0;i<=limit;i++){
	    // use serial number of array to avoid duplication
	    if(delDuplication[i]==0){
		sum+=i;
	    }
	}
      
	System.out.println("sum="+sum);
    }