public class Main { public static void main(String[] args) { Scanner in = new Scanner(System.in); String s = in.nextLine().trim(); Stack<Character> stk = new Stack<>(); for(int i=0; i<s.length(); i++){ char c = s.charAt(i); boolean flag = false; while(!stk.isEmpty() && c ==')' && stk.peek() == '('){ stk.pop(); flag = true; } if(flag){ stk.push('('); }else{ stk.push(c); } } System.out.println(stk.size()); } }