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 PHP7 (7.0.15) (judge verdict: Accepted)

<?php

	$data = explode(" ", trim(fgets(STDIN)));
	$n = $data[0];
	$a = $data[1];
	$b = $data[2];
	if($n == 1){
	    if($a == $b) echo 1;
	    else echo 0;
	} else {
	    if($a>$b) echo 0;
	    else{
	        $n -= 2;
	        echo ($b - $a) * $n + 1;
	    }
	}
	
?>