这里~

//MADE BY Y_is_sunshine;
//#include <bits/stdc++.h>
//#include <memory.h>
#include <algorithm>
#include <iostream>
#include <cstdlib>
#include <cstring>
#include <sstream>
#include <cstdio>
#include <vector>
#include <string>
#include <cmath>
#include <queue>
#include <stack>
#include <map>
#include <set>

#define INF 0x3f3f3f3f
#define MAXN 305
const int mod = 1e9 + 7;

using namespace std;

int dp[MAXN][MAXN];
int d[MAXN];
string s1;


bool ok(int x, int y) {
	if (s1[x] == '(' && s1[y] == ')')
		return true;
	if (s1[x] == '[' && s1[y] == ']')
		return true;
	return false;
}

int main()
{

	freopen("data.txt", "r", stdin);


	
	while (cin >> s1) {
		if (s1 == "end")
			break;
		memset(dp, 0, sizeof(dp));
		int N = s1.size();
		s1.insert(s1.begin(), ' ');
		for (int len = 1; len < N; len++) {
			for (int i = 1; i + len <= N; i++) {
				int end = i + len;
				if (ok(i, end))
					dp[i][end] = max(dp[i][end], dp[i + 1][end - 1] + 2);
				for (int k = i; k < end; k++)
					dp[i][end] = max(dp[i][end], dp[i][k] + dp[k + 1][end]);
			}
		}
		
		cout << dp[1][N] << endl;

	}

	

	freopen("CON", "r", stdin);
	system("pause");
	return 0;
}