#include <cstring>

 #include <cstdio>

 #include <iostream>

 #include <string>

 using namespace std;

 #define N 105

 int dp[][];

 string s;

 int main() {

     while(cin >> s) {

         if(s == "end") break;

         int n = s.length();

         memset(dp, , sizeof(dp));

         for(int len = ; len < n; len++) {

             for(int i = ; i + len < n; i++) {

                 int j = i + len;

                 if(s[i] == '(' && s[j] == ')' || s[i] == '[' && s[j] == ']') dp[i][j] =  + dp[i+][j-];

                 for(int k = i; k < j; k++)

                     if(dp[i][j] < dp[i][k] + dp[k+][j]) dp[i][j] = dp[i][k] + dp[k+][j];

             }

         }

         printf("%d\n", dp[][n-]);

     }

     return ;

 }