s = ''  # Current string state
history = []  # Stack of undo operations (each is a function that reverts a change)

for _ in range(int(input())):
    command = input().rstrip().split()
    
    match command[0]:
        case '1':  # Append operation
            # Save undo operation (removes the appended part)
            # Using lambda with default arg to capture current command[1] length
            history.append(lambda s, chars_to_remove=len(command[1]): s[:-chars_to_remove])
            # Perform the append
            s += command[1]
            
        case '2':  # Delete operation
            chars_to_delete = int(command[1])
            # Save undo operation (re-adds the deleted portion)
            # Store the deleted substring as default arg to avoid late binding issues
            history.append(lambda s, deleted_part=s[-chars_to_delete:]: s + deleted_part)
            # Perform the deletion
            s = s[:-chars_to_delete]
            
        case '3':  # Print character at index
            print(s[int(command[1]) - 1])
            
        case '4':  # Undo last operation
            if history:  # Only undo if there's history
                # Apply the most recent undo operation
                s = history.pop()(s)