Operators and For Loop:Sum or Product

import java.util.Scanner;
public class Main {
	
	public static void main(String[] args) {
	Scanner s=new Scanner(System.in);
    int N=s.nextInt();
    int C=s.nextInt();
    int sum=0;
    int product=1;
    if(C==1)
    {
        for(int i=0;i<=N;i++)
        {
            sum=sum+i;
           
        }
         System.out.println(sum);
    }
        else if(C==2){
            for(int i=1;i<=N;i++)
            {
                product=product*i;
                
            }
              System.out.println(product);
        }
        else
        {
            System.out.println("-1");
        }

	}
}