public ArrayList<Integer> getUnreliableUserList(){
		if(clusters.size()==0){
			System.out.println("clusters size = 0");
		}
		int min = clusters.get(0).getClusterSize();
		ArrayList<Integer> indexList = new ArrayList<Integer>();
		
		for(int i=0;i<clusters.size();i++){
			if (clusters.get(i).getClusterSize()!=0&&min>clusters.get(i).getClusterSize()){
				min = clusters.get(i).getClusterSize();
			}
		}

		for(int i=0;i<clusters.size();i++){
			if (min==clusters.get(i).getClusterSize()){
				indexList.add(i);
			}
		}
		ArrayList<Integer> unreliableUser = new ArrayList<Integer>() ;
		for(int i=0; i<indexList.size();i++){
			for (int j=0; j<min; j++){
				unreliableUser.add(clusters.get(indexList.get(i)).getUsernum(j));
			}
		}
		
		return unreliableUser;
	}