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 PHP (5.6.30) (judge verdict: Accepted)

<?php
list($n,$a,$b) = explode(" ", trim(fgets(STDIN)));

if($n == 1){
if($a == $b){
echo 1;
}else{
echo 0;
}
}else{
if($a > $b){
echo 0;
}elseif($a == $b){
echo 1;
}else{
$n = $n - 2;
$d = ($b - $a) * $n + 1;
echo $d;
}
}