def str2float(s):
    def char2int(s):
        return {'0':0, '1':1, '2':2, '3':3, '4':4, '5':5, '6':6, '7':7, '8':8,\
            '9':9}[s];
    def fn(x, y):
        return x*10 + y;
    l = str(s).split('.');
    return reduce(fn, map(char2int, l[0]+l[1])) / 10**len(l[1]);