How can i solve this err in java : I'm KIMYONGGEE

I wonder what's wrong with this **JAVA project**

    class Sample {
	public int a;
	private int b;
	int c;
	}
    public class ex {
	public static void main(String[] args) {
		Sample aClass = new Sample();
		aClass.a = 10;
		aClass.b = 10;
		aClass.c = 10;
	}
}