Q = int(input())
S = str()
prev = []

operations = []
for i in range(Q):
    operations.append(input().split(" "))
    
for i, op in enumerate(operations):
    match op[0]:
        case "1":
            prev.append(S)
            S += op[1]
        case "2":
            prev.append(S)
            S = S[:-int(op[1])]
        case "3":
            print(S[int(op[1])-1])
        case "4":
            S = prev[-1]
            prev.pop()