Input a binary into a variable in C#?

I would like to make a program in wich the user inputs a number ( binary like 0 and 1 ). The program interprets it as string then put it in a variable and add it with another binary number. I don't know how should I declare the variable witch stores the first binary number? In decimal is simple but in binary I don't know how to do it...|||int





Convert the binary strings to an integer.


Add the integers.


Convert the result back to a binary string.