#include <bits/stdc++.h>
#define in freopen("input.txt","r",stdin);
#define out freopen("output.txt","w",stdout);
using namespace std;
int main()
{
//   in;
//   out;
   string s;
   cin >> s;
   int ans = 0 , ind1 = 0 , ind2 = 0 , i , j;
   for( i = 0; i < s.size(); i ++ ){
      int kol = 0;
      for( j = i; j < s.size(); j ++ ){
         if( s[j] == '(' )kol ++;
         else kol --;
         if( kol < 0 )break;
         if( kol == 0 ){
            if( ans < j - i + 1 ){
               ans = j - i + 1;
               ind1 = i;
               ind2 = j;
            }
         }
      }
   }
   for( i = ind1; i <= ind2; i ++ )cout << s[i];
   cout << endl;
}