921. Minimum Add to Make Parentheses Valid

class Solution {
    public int minAddToMakeValid(String s) {
        Stack<Character> stack=new Stack<>();
        int count=0;
        for(int i=0;i<s.length();i++){
            if(s.charAt(i)=='('){
                stack.push('(');
                count++;
            }else if(s.charAt(i)==')'){
                if(stack.isEmpty()){
                    count++;
                }else if(!stack.isEmpty() && stack.peek()=='('){
                    stack.pop();
                    count--;
                }
            }
        }

        return count;

    } 
}