#include <iostream>

#include <cstring>

#include <algorithm>

#include <string>

#include <vector>

using namespace std;

class Solution {

public:

    int longestValidParentheses(string s) {

        int n = s.length();

        vector<vector<int> > dp(n+);

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

            for(int j=;j<n;j++)

                dp[i].push_back();

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

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

                j=i+len-;

                if((s[i] == '(' && s[j] == ')') || (s[i] == '[' && s[j] == ']'))

                    dp[i][j] = max(dp[i][j],dp[i+][j-]+);

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

                    dp[i][j] = max(dp[i][j],dp[i][k]+dp[k+][j]);

            }

        }

        return dp[][n-];

    }

};

int main()

{

    Solution a;

    string s;

    while(cin>>s) {

        if(s == "end") break;

        cout<<a.longestValidParentheses(s)<<endl;

    }

    return ;

}