#include<stdio.h>

char buffer[256];
int input, nest, write_index;

int main()
{
   while( (input = getchar()) != EOF )
      buffer[(nest += input - 93 ? input == 91 : -1) < 0 && input - 93 ? write_index++ : 255] = input;
   puts(buffer);
   return 0;
}