Problem:
Score : 200 points

Problem Statement

Snuke has N integers. Among them, the smallest is A, and the largest is B.
We are interested in the sum of those N integers. How many different possible sums there are?

Constraints

1 ≤ N,A,B ≤ 10^9

A and B are integers.

Input

Input is given from Standard Input in the following format:

N A B

Output

Print the number of the different possible sums.

Sample Input 1

4 4 6

Sample Output 1

5

There are five possible sums: 18=4+4+4+6, 19=4+4+5+6, 20=4+5+5+6, 21=4+5+6+6 and 22=4+6+6+6.

Sample Input 2

5 4 3

Sample Output 2

0

Sample Input 3

1 7 10

Sample Output 3

0

Sample Input 4

1 3 3

Sample Output 4

1

Solution in Lua (5.3.2) (judge verdict: Accepted)

local n = io.read("*n")
local a = io.read("*n")
local b = io.read("*n")
local function add(n,a,b)
	if b < a then
		print(0)
		return
	end
	if n == 1 then
		if a ~= b then
			print(0)
			return
		else
			print(1)
			return
		end
	elseif n == 2 then
			print(1)
			return
	end
	local total = a + b
	local min = total + (n - 2) * a
	local max = total + (n-2)*b
	print( max - min + 1)
end

add(n,a,b)