def kdmt(s):
    return (int(s[0])>int(s[2]))==(int(s[2])<int(s[4]))

def main():
    s=input()
    ans=''
    if kdmt(s.replace('?','1')):
        ans+='1'
    if kdmt(s.replace('?','4')):
        ans+='4'
    print(ans)

if __name__ == '__main__':
    main()