public void printParentheses(int l, int r, char ch[], int count) {
		if(l==0 && r==0)
			System.out.println(ch);
		if( l<0 || r<1) return;
		else {
			if(l>0) {
				ch[count] = '(';
				printParentheses(l-1, r, ch, count+1);
			} 
			if(r>l) {
				ch[count]=')';
				printParentheses(l, r-1, ch, count+1);
			}
		}
	}