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 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>

int main()
{
    long long n,a,b,num = 0;
    scanf("%lld %lld %lld",&n,&a,&b);
    if(n == 1)
    {
        if(a == b)
            num = 1;
        else
            num = 0;
    }
    else
    {
        if(a == b)
            num = 1;
        else
            num = (n - 2) * (b - a) + 1;
    }
    if(a > b)
        num = 0;
    printf("%d\n",num);
    return 0;
}