class text_editor:
    def __init__(self):
        self.S = ""
        self.op_stack = []
        self.tgt_stack = []
           
    def w_append(self,tgt):
        s1 = list(self.S)
        s1.append(tgt)
        self.S = ''.join(s1)
        self.op_stack.append('1')
        self.tgt_stack.append(len(tgt))
        
    def k_delete(self,tgt):
        s1 = list(self.S)
        self.tgt_stack.append(''.join(s1[-int(tgt):]))
        s1 = s1[:-int(tgt)]
        self.S = ''.join(s1)
        self.op_stack.append('2')
        
    def k_print(self,tgt):
        s1 = list(self.S)
        print(f'{s1[int(tgt) -1]}')

    def undo(self):
        s1 = list(self.S)
        op = self.op_stack.pop(-1)
        if op == '1':
            s1 = s1[:-int(self.tgt_stack.pop(-1))]
        elif op == '2':
            s1.append(self.tgt_stack.pop(-1))
        if s1:
            self.S = ''.join(s1)
        else:
            self.S = ""
        
    def receive_ops(self,op,tgt):
        if op == '1':
            self.w_append(tgt)

        elif op == '2':
            self.k_delete(tgt)

        elif op == '3':
            self.k_print(tgt)
        elif op == '4':
            self.undo()
                   
if __name__ == '__main__':
    q = int(input())
    S = ""
    tgt = None
    op = ''
    t = text_editor()
    for _ in range(q):
        x = input().split()
        op = x[0]
        if len(x) > 1:
            tgt = x[1]
        t.receive_ops(op,tgt)