def str2float(s):
    l = s.split('.')
    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]
    return reduce(lambda x, y: x * 10 + y, map(char2num, l[0])) + reduce(lambda x, y: x * 10 + y, map(char2num, l[1])) / 10 ** len(l[1])