#!/usr/bin/python


stack = []


def pushit():
    stack.append(raw_input('enter new string: ').strip())


def popit():
    if len(stack)==0:
        print 'cannot pop from an empty stack'
    else:
        print 'removed [', stack.pop(),']'


def viewstack():
    print stack


CMDs={'u':pushit,'o':popit,'v':viewstack}


def showmenu():
    pr="""
p(U)sh
p(O)p
(V)iew
(Q)uit


enter choice: """


    while True:
        while True:
            try:
                choice = raw_input(pr).strip()[0].lower()
            except (EOFError,KeyboardInterrupt,IndexError):
                choice = 'q'
        
            print '\nyou picked: [%s]' % choice
            if choice not in 'uovq':
                print 'invalid option, try again'
            else :
                break
        if choice == 'q':
            break
        CMDs[choice]()


if __name__ == '__main__':
    showmenu()

#!/usr/bin/python


queue = []


def enqueue():
    queue.append(raw_input('enter new string: ').strip())


def dequeue():
    if len(queue)==0:
        print 'cannot pop from an empty queue'
    else:
        print 'removed [', queue.pop(0),']'


def viewqueue():
    print queue


CMDs={'u':enqueue,'o':dequeue,'v':viewqueue}


def showmenu():
    pr="""
p(U)sh
p(O)p
(V)iew
(Q)uit


enter choice: """


    while True:
        while True:
            try:
                choice = raw_input(pr).strip()[0].lower()
            except (EOFError,KeyboardInterrupt,IndexError):
                choice = 'q'
        
            print '\nyou picked: [%s]' % choice
            if choice not in 'uovq':
                print 'invalid option, try again'
            else :
                break
        if choice == 'q':
            break
        CMDs[choice]()


if __name__ == '__main__':
    showmenu()