from functools import reduce

def str2float(s):

    def text2(x,y):

        return x*10+y

    def text3(x,y):

        return x/10+y

    s1,s2=s.split('.')#根据'.'将str分成两个子串

    s2=s2[::-1]#取倒序

    a1=reduce(text2,map(int,s1))

    a2=reduce(text3,map(int,s2))/10

    return a1+a2