I need 70 or more input pins for the Arduino -how to do this? I have some SN74HC165N, CD4021B chips. How many (minimally) such ICs would I need to get 70 inputs to an Arduino Uno? What is the exact circuit diagram and the code? Im not sure how the wring cascades into each of the chips to make it grow to over 70 inputs, or what the code is for the 70 input circuit. I do understand how to use one of those ICs though. My second easier question is -is there an development board with 70 or more inputs?

CD4021B,SN74HC165N are the chips, you know the ones, that has a parallel input pins that are listened to by latch pin, and the clock pins such outputs the parallel data into the serial data-so I am interested with solution with this pin because I know how it works.

It is for sure 70 pins that are required -not any less-I am sure of that. Because the inputs cannot be further simplified to less than 70. The reason the inputs are 70 is because the algorithm used has 70 free variables in it. Hence by definition it uses 70 or more variables. The input for each of the 70 inputs can be a digital high or a digital low but this is not known before hand. So it cant be simplified because it like saying you can simplfy the information from 70 or more sensors at runtime, and each sensor has an unpredictable value. Anyway this explanation is moving away from the point of my question. I just want to know the circuit that does 70 inputs or more using the mentioned IC-I can live with that answer even if its not the most efficient.
The best way I know to do it is by using the MCP23017, which gives you 16 extra GPIOs via I²C communication. They can be configured for both input and/or output. I've done it myself and it worked like a charm. It has 3 pins for dynamic addressing (3 bits), which allows you to use up to 8 (0..7) MCP23017 for a total of 128 extra GPIOs. 
This is the chip datasheet:
(http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf)
There's a lot of examples about its use on the internet. Just google for "MCP23017 arduino" and you'll find them. For example:
http://tronixstuff.com/2011/08/26/tutorial-maximising-your-arduinos-io-ports/