class StackMax:
    def __init__(self):
        self.arr = []

    def push(self, x):
        self.arr.append(x)

    # def get_length(self):
    #     return len(self.arr)

    def pop(self):
        if len(self.arr):
            return self.arr.pop()
        return 'error'

    def get_max(self):
        if len(self.arr):
            return max(self.arr)
        return 'None'


n = int(input())
new_stack = StackMax()
for i in range(n):
    operation = input()
    if operation.startswith('get_max'):
        print(new_stack.get_max())
    elif operation.startswith('push'):
        value = operation.split()[-1]
        new_stack.push(value)
    elif operation.startswith('pop'):
        call_back = new_stack.pop()
        if call_back == 'error':
            print(call_back)