C

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <string>
#include <map>
#include <cmath>
#include <vector>

#define Faster ios::sync_with_stdio(false),cin.tie(0)
#define Read freopen("in.txt","r",stdin),freopen("out.txt","w",stdout)
#define Close fclose(stdin),fclose(stdout)
const int maxn = 150;
using namespace std;
const int MOD = 1e9+7;
typedef long long ll;

ll dp[maxn][maxn];
string s;

void solve(){
    int len = s.size();
    memset(dp, 0, sizeof(dp));

    for(int i = 1;i < len;i++){
        for(int j = 0;j + i < len;j++){
            int k = i+j;
            if((s[j] == '(' &&  s[k] == ')') || (s[j] == '[' && s[k] == ']'))
                dp[j][k] = dp[j+1][k-1] + 2;
            for(int l = j;l < k;l++){
                dp[j][k] = max(dp[j][l] + dp[l+1][k],dp[j][k]);
            }
        }
    }
    cout << dp[0][len-1] << endl;
}

int main(){
    Faster;
    // string s;
    while(cin >> s){
        if(s == "end"){
            break;
        }
        solve();
    }
    return 0;
}