n = int(input())
stk = []
for _ in range(n):
    s = list(input().split())
    if s[0] == "push":
        stk.append(int(s[1]))
    elif s[0] == "pop":
        if len(stk) > 0:
            stk.pop()
        else:
            print("Empty")
    elif s[0] == "query":
        if len(stk) > 0:
            print(stk[-1])
        else:
            print("Empty")
    elif s[0] == "size":
        print(len(stk))