//edited by Eddy
//from BeiHang Univ
//any questions,contact oeddyo@gmail.com

#include <iostream>
using namespace std;
#define MAX 101

   int res[MAX][MAX];
   int pos[MAX][MAX];

void output(char a[],int b,int e)
{
    if(b>e)
        return ;
    if(pos[b][e]==-1)
    {
        cout<<a[b];
        output(a,b+1,e-1);
        cout<<a[e];
        return ;
    }
    if(b==e)
    {
        if(a[b]=='('||a[e]==')')
            cout<<"()";
        else if(a[b]=='['||a[e]==']')
            cout<<"[]";
        return ;
    }
    output(a,b,pos[b][e]);
    output(a,pos[b][e]+1,e);
}

int main()
{
   char s[120];
   while(cin.getline(s,101))
   {
       memset(res,0,sizeof(res));
       memset(pos,0,sizeof(pos));
       int s_size=strlen(s);

       for(int i=0;s[i];i++)
       {
           res[i][i]=1;
           for(int j=i-1; j>=0; j--)
           {
               if(s[j]=='('&&s[i]==')'||s[j]=='['&&s[i]==']')
               {
                   res[j][i]=res[j+1][i-1];
                   pos[j][i]=-1;                                      //标记-1即不用多补
               }
               else
               {
                   res[j][i]=10000000;
               }

               for(int k=j;k<i;k++)                         //经典代码。。。多理解
               {
                   int t=res[j][k]+res[k+1][i];
                   if(t<res[j][i])
                   {
                       res[j][i]=t;
                       pos[j][i]=k;
                   }
               }

           }
       }
       output(s,0,s_size-1);
       cout<<endl;
   }
    return 0;
   
}