#include <iostream>
using namespace std;

char x[200];
int longest[101][101];
int getLongest(int i1, int i2) {
  if (longest[i1][i2] != -1)
    return longest[i1][i2];

  int val = 0;
  if (i1 > i2)
    return 0;
  val >?= getLongest(i1+1, i2);
  val >?= getLongest(i1, i2-1);
  
  for (int j1 = i1; j1 <= i2; j1++)
    for (int j2 = j1; j2 <= i2; j2++)
      if ( (x[j1] == '(' && x[j2] == ')') || 
	   (x[j1] == '[' && x[j2] == ']')) {
	val >?= 2 
	  + getLongest(i1,j1-1)
	  + getLongest(j1+1,j2-1)
	  + getLongest(j2+1, i2);
      }

  longest[i1][i2] = val;
  return val;
}

int main() {
  int i, j;
  while (1) {
    cin >> x;
    if (x[0] == 'e')
      return 0;
    for (i = 0; i < 101; i++)
      for (j = 0; j < 101; j++)
	longest[i][j] = -1;
    cout << getLongest(0, strlen(x)-1) << endl;
  }
}