For loop with a user input problem

[barokim 0]

Hi !
     I`m writing a mining programme, but i`ve run into a problem. I `ve set the program to ask me for number of tunnels in the mine, but every time my robot should use the number that i`ve inputed, it just stops and does nothing. Probably something wrong with my for loop... 

 

Here is the whole code : (Lines i`m talking about are 47th. 48th and 54th)

http://pastebin.com/if94es5Q

 

And this are just three lines of code im concerned about :
 

1. io.write("Ilosc tuneli: ")
2. b = io.read()
   
   

   1. for i = 1,b do --Zmień drugą liczbę żeby zmienić ilość odnóg--

   
   
    

[barokim 0]

Sorry, the problem lied somewhere else - i`ve tried to use term.write() earlier, and when i`ve tried to repair the problem, i accidentaly deleted a = 0 command