def str2float(s):
    def char2num(s):
        return {'0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5, '6': 6, '7': 7, '8': 8, '9': 9}[s]
    x,y=s.split('.')
    return reduce(lambda a,b:a*10+b,map(char2num,x))+reduce(lambda d,e:d*10+e,map(char2num,y))/pow(10,len(y))