Passing function as argument

Question

I know this won't work, but if you can see what I'm trying to do, I would like help to make it work:

void f1(float input){

        listbox.Add(input*1);

}

void f2(float input){

        listbox.Add(input*2);

}

void f3(function *inputFunction, argument *inputArgument){

        inputFunction(inputArgument);

}

void main(){

        f3(f1 , 1);

}

How do I make it possible to call f3, so that it has acces to either f1 or f2, with whatever argument I want?