#include<set>

#include<map>

#include<cmath>

#include<queue>

#include<cstdio>

#include<cstring>

#include<algorithm>

typedef long long ll;

using namespace std;

const int maxn =  + ;

const int MOD = 1e9 + ;

const int INF = 0x3f3f3f3f;

int dp[maxn][maxn];

char s[maxn];

bool ok(int i, int j){

    if(s[i] == '(' && s[j] == ')') return true;

    if(s[i] == '[' && s[j] == ']') return true;

    return false;

}

int main(){

    while(~scanf("%s", s + )){

        if(strcmp(s + , "end") == ) break;

        memset(dp, , sizeof(dp));

        int n = strlen(s + );

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

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

                int j = i + len - ;

                if(ok(i, j)){

                    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]);

                }

            }

        }

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

    }

    return ;

}