#include <string>
#include <deque>
#include <vector>
#include <iostream>
using namespace std;

int rec_children(const vector <int> &v, int index)
{
  int recursive_answer, nc, a;
  int i;

  if (v[index] == index+1) return 0;    // Base case -- if it's a single node, return 0.
 
  nc = 0;
  recursive_answer = 0;
  for (i = index+1; i != v[index]; i = v[i]+1) {    // Traverse the subtrees
    nc++;                                           // Use nc to count the number of children.
    a = rec_children(v, i);                         // Compute the max children of each subtree.
    if (a > recursive_answer) recursive_answer = a;
  }
  if (nc > recursive_answer) recursive_answer = nc;
  return recursive_answer;                          // Return one plus the max children.
}

int max_children(const string &s)
{
  vector <int> v;
  deque <int> stack;
  size_t i, j;

  v.resize(s.size(), -1);                    // Create v by using st as a stack
  for (i = 0; i < s.size(); i++) {
    if (s[i] == '(') {                         // Push the index onto the stack on '('
      stack.push_front(i);
    } else {                                   // Otherwise pop the index of the corresponding '('
      j = stack[0];
      stack.pop_front();
      v[j] = i;
    }
  }
  return rec_children(v, 0);                   // Return the max of children and answers for the children.
}

int main(int argc, char **argv)
{
  string s;

  if (argc != 2) {
    cerr << "usage: a.out string" << endl;
    exit(1);
  }

  s = argv[1];
  cout << max_children(s) << endl;
  return 0;
}