如果有 months = "Jan.Feb.Mar.Apr.May.Jun.Jul.Aug.Sep.Oct.Nov.Dec."，编写程序，用户输入月份数字，输出月份缩写

months = "Jan.Feb.Mar.Apr.May.Jun.Jul.Aug.Sep.Oct.Nov.Dec."
month_num = int(input("请输入月份数字："))

if month_num >= 1 and month_num <= 12:
start_index = (month_num - 1) * 4
end_index = start_index + 3
month_abbr = months[start_index:end_index+1]
print("月份缩写为：", month_abbr)
else:
print("输入的月份数字不正确")