请输入星期几的第一个字母来判断一下是星期几，如果第一个字母一样，则继续判断第二个字母

分析：

用情况语句比较好，如果第一个字母一样，则判断用情况语句或if语句判断第二个字母。

法一：

letter = input("请输入：")

if letter == 'S':
    print('请输入第二个字符：')
    letter = input("please input:")
    if letter == 'a':
        print('Saturday')
    elif letter == 'u':
        print('Sunday')
    else:
        print('data error')

elif letter == 'F':
    print('Friday')

elif letter == 'M':
    print('Monday')

elif letter == 'T':
    print('please input second letter')
    letter = input("please input:")

    if letter == 'u':
        print('Tuesday')
    elif letter == 'h':
        print('Thursday')
    else:
        print('data error')

elif letter == 'W':
    print('Wednesday')
else:
    print('data error')      

def judge(first,list):
    li=[]
    first = first.upper()
    for a in list:
        if re.match(first,a):
            li.append(a)
    if len(li)==1:
        print(li[0])
    else:
        second=input('请输入第二个字母：')
        for b in li:
            if re.match(first+second,b):
                print(b)
list=['Monday','Tuesday','Wednesday','Thursday','Friday','Saturday','Sunday']
first=input('请输入第一个字母：')
judge(first,list)      

week=['Monday','Tuesday','Wednesday','Thursday','Friday','Saturday','Sunday']

def find(s,week):
    a = input("please input a letter")
    s=s+a
    result=[]
    for i in week:
        if i.startswith(s):
            result.append(i)
    
    if len(result)==1:
        return result
    else:
        return find(s,result)

s=''
print(find(s,week))