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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.math.BigInteger;
import java.util.*;
public class Main {
	
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        long N = sc.nextLong();
        long A = sc.nextLong();
        long B = sc.nextLong();
        
        if (A > B || N < (A-B+1)) {
        	System.out.println(0);
        	return;
        }
        
        
        //処理
        N -= 2;
        
        String ans = BigInteger.valueOf(B).multiply(BigInteger.valueOf(N)).subtract(BigInteger.valueOf(A).multiply(BigInteger.valueOf(N))).add(BigInteger.ONE).toString(10);
        
        System.out.println(ans);
    }
}