def push():
    n = int(input("Enter the number you want to add in Stack :- "))
    stack.append(n)
def pop():
    if stack ==[]:
        print("Stack Underflow")
    else:
        print(stack.pop())
def peep():
    if stack ==[]:
        print("Stack Underflow")
    else:
        print(stack[-1])
def display():
    for i in range(len(stack)-1,-1,-1):
        print(stack[i])
stack=[]
while True:
    n = int(input("""Enter your Choice :-
        Press 1 for Push operation.
        Press 2 for POP  operation.
        Press 3 for Peep operatin.
        Press 4 for Display operation.
        Press 5 for Exit.
"""))
    if n==1:
        push()
    elif n==2:
        pop()
    elif n==3:
        peep()
    elif n==4:
        display()
    else:
        break