SumPrimeNotPrime

import java.util.Scanner;
public class SumPrimeNonPrime {
    public static void main(String[] args) {
        Scanner input=new Scanner(System.in);
        int sumPrime=0,sumNotPrime=0;


        while(true){
            String str=input.nextLine();
            boolean flag=false;

            if(str.equals("stop")){
                break;
            }
            int number=Integer.parseInt(str);
            if(number<0){
                System.out.println("Number is negative.");
                continue;
            }
            for(int i=2;i<=number/2;++i){
                if(number%i==0){
                    flag=true;
                    break;
                }
            }
          if (number==1) {
            flag=true;
          }
            if(!flag){
                sumPrime+=number;
            }else{
                sumNotPrime+=number;
            }

        }
        System.out.println("Sum of all prime numbers is: "+sumPrime);
        System.out.println("Sum of all non prime numbers is: "+sumNotPrime);
    }
}