I am an Erlang beginner and am trying to make a simple command-line application where the user enters the width and height of a floor, the cost per square foot of flooring and they are returned a price. Essentially I'm just accepting three integer values and returning the product.

```
23> c(costcalc).
{ok,costcalc}
24> costcalc:start().
Calculate the cost of flooring based on width, height, and cost per square foot.

Width in feet: 5
Height in feet: 5
Cost in dollars per square foot: $4
** exception error: an error occurred when evaluating an arithmetic expression in function  costcalc:start/0 (costcalc.erl, line 23)

```

Here is the code I am using:

```
start() ->
  io:format("Calculate the cost of flooring based on width, height, and cost per square foot.\n"),
  W = string:to_integer(io:get_line("Width in feet: ")),
  H = string:to_integer(io:get_line("Height in feet: ")),
  C = string:to_integer(io:get_line("Cost in dollars per square foot: $")),
  Cost = W * H * C,
  io:fwrite(Cost).

```

Line 23 is `Cost = W * H * C,` which should be 100. When I run `5 * 5 * 4.` in the shell directly it calculates without issue. I should also note that this happens whether or not I use string:to\_integer() which I would imagine I can get by without.

What am I missing?