1963.minimum number of swaps to make tthe string balanced

class Solution {
    public int minSwaps(String s) {
        Stack<Character> st=new Stack<>();
        int c=0;
        for(int i=0;i<s.length();i++){
            if(s.charAt(i)=='['){
                st.add(s.charAt(i));
            }
            else{
                if(!st.isEmpty() && st.peek()=='['){
                    st.pop();
                }
                else{
                    c++;
                }
            }
        }
        return c%2==0?c/2:(c+1)/2;
    }
}