import sys

class TextEditor():
    def __init__(self):
        self.text = ""
        self.op_stack = []
        
    def append(self, s, undo=False):
        if not undo:
            self.op_stack.append((1, s))
        self.text += s
          
    def delete(self, k, undo=False):
        if not undo:
            self.op_stack.append((2, self.text[-k:]))
        self.text = self.text[:-k]
    
    def _print(self, k):
        print(self.text[k-1])

    def undo(self):
        if self.op_stack:
            op_type, s = self.op_stack.pop()
            
        match op_type:
            case 1:
                self.delete(len(s), undo=True)
            case 2:
                self.append(s, undo=True)
            case _:
                print('Cannot Undo Command!', file=sys.stderr)
                exit(1)
            
if __name__ == "__main__":
    q = int(input())
    editor = TextEditor()
    
    for _ in range(q):
        op = input()

        match int(op[0]):
            case 1:
                editor.append(op.split()[1])
            case 2:
                editor.delete(int(op.split()[1]))
            case 3:
                editor._print(int(op.split()[1]))
            case 4:
                editor.undo()
            case _:
                print('Unknown Command!', file=sys.stderr)
                exit(1)