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

class In {

	private $buf = [];
	private $count = 0;
	private $pointer = 0;

	public function nextLine() {
		$ret = '';
		if($this->hasNext()){
			while($this->hasNext()){
				$ret .= $this->next();
			}
		}else{
			$ret = trim(fgets(STDIN));
		}

		return $ret;
	}

	public function next() {
		if(!$this->hasNext()) {
			$str = trim(fgets(STDIN));
			$this->buf = explode(' ',$str);
			$this->count = count($this->buf);
			$this->pointer = 0;
		}

		return $this->buf[$this->pointer++];
	}

	public function hasNext() {
		return $this->pointer < $this->count;
	}

	public function nextInt() {
		return (int)$this->next();
	}

	public function nextDouble() {
		return (double)$this->next();
	}
}

class Out {
	public function println($str = '') {
		echo $str . PHP_EOL;
	}
}

$in = new In();
$out = new Out();

$N = $in->nextInt();
$A = $in->nextInt();
$B = $in->nextInt();

if ($A > $B) {
	$out->println(0);
	return;
}

if ($N <= 1) {
	if ($A == $B) {
		$out->println(1);
	} else {
		$out->println(0);
	}
	return;
}

$ans = ($N - 2) * ($B - $A) + 1;

$out->println($ans);

?>