# -*- coding: utf-8 -*-

from functools import reduce

def str2float(s):
    if(isinstance(s,str) == False):
        return
    def f1(x,y):
        return x * 10 + y
    def f2(c):
        return {'0':0,'1':1,'2':2,'3':3,'4':4,'5':5,'6':6,'7':7,'8':8,'9':9,'.':'.'}[c]
    L = list(map(f2,s))
    n = 0
    while n < len(L):
        if(L[n] == '.'):
            break;
        n = n + 1
    L1 = L[0:n]
    L2 = L[n+1:]
    if(L2 == []):
        L2 = [0,0]
    if(L1 == []):
        L1 = [0,0]
    return reduce(f1,L1) + reduce(f1,L2) / pow(10,len(L2))