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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
class Program
{
    static void Main(string[] args)
    {
        long[] a = Read.Ints();HashSet<long> s = new HashSet<long> { };
        Console.WriteLine(Math.Max(0,a[2]*(a[0]-1)+a[1]+1-(a[2]+(a[0]-1)*a[1])));
        Console.ReadLine();
    }
    public static Boolean uso() { return false; }
    public static int gcd(int a,int b)
    {
        while (true)
        {
            if (a == 0) { return b; }
            if (b == 0) { return a; }
            if (a > b) { a -= b; }
            else { b -= a; }
        }
    }
    public static int lcm(int a,int b)
    {
        return a * b / gcd(a,b);
    }
    public static bool IsPrime(long n)
    {
        if (n < 2) return false;
        if (n == 2) return true;

        for (int i = 2; i < n; i++)
        {
            if (n % i == 0) return false;
        }
        return true;
    }

}
public static class Read
{
    public static void outl(string n = "") { Console.WriteLine(n); return; }
    public static int Int()
    {
        return int.Parse(Console.ReadLine());
    }
    public static long[] Ints()
    {
        return Console.ReadLine().Split().Select(long.Parse).ToArray();
    }
    public static string Str() { return Console.ReadLine(); }
    public static string[] Strs() { return Console.ReadLine().Split(); }
}