n_opperations = int(input().strip())
operations = list()

for _ in range(n_opperations):
    operations.append(input().strip())

string = str()
done = list()

for ops in operations:
    if ops[0] == '1':
        done.append(ops)
        string += ops[2:]
    elif ops[0] == '2':
        k = int(ops[2:])
        done.append((ops[0], ' ', string[-k:]))
        string = string[:-k]
    elif ops[0] == '3':
        print(string[int(ops[2:])-1])
    elif ops[0] == '4':
        if done[-1][0] == '1':
            string = string[:-len(done[-1][2:])]
            done.pop()
        else:
            string += done[-1][2]
            done.pop()