//#include<bits/stdc++.h>

 #include <cstdio>

 #include <cstring>

 #include <algorithm>

 using namespace std;

 char s[];int f[][];

 int DP(int n){

   memset(f,,sizeof(f));

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

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

       if((s[l]=='('&&s[r]==')')||(s[l]=='['&&s[r]==']'))f[l][r]=max(f[l][r],f[l+][r-]+);

       for(int i=l;i<r;i++)f[l][r]=max(f[l][r],f[l][i]+f[i+][r]);

     }

   return f[][n];

 }

 int main(){

   while(scanf("%s",s+)&&s[]!='e')printf("%d\n",DP(strlen(s+)));

   return ;

 }