function nesting(s: string): number {
  if (s === "") {
    return 1;
  }

  const stack: string[] = [];
  for (const v of s) {
    if (v === ")") {
      if (stack.length === 0 || stack.pop() !== "(") {
        return 0;
      }
    } else if (v) {
      stack.push(v);
    }
  }

  return stack.length === 0 ? 1 : 0;
}