public class MyClass{
	public void printText(String text){
		System.out.println(text);
	}

	public void writeText(String text1,String text2){
		System.out.println(text1);
		System.out.println(text2);
	}

	public int sum(int value1,int value2){
		return value1+value2;
	}

	public String concat(String value1,String value2)
	throws IllegalArgumentException{
		if(value1==null){
			throw new IllegalArgumentException("value1 is null");
		}
		if(value2==null){
			throw new IllegalArgumentException("value2 is null");
		}

		return value1+value2;

	}
}