public class Solution{
	public int reverse(int x){
		StringBuffer sb = new StringBuffer();
		if(x < 0){
			sb.append("-");
		}
		
		System.out.println("X:"+x);
		return 0;
	}
	
	public static void main(String[] args){
		System.out.println("hello world");
	}
}

add Solution.java for problem7