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: Accepted)

#include<stdio.h>

int main(void){
  long long N,A,B;
  long long i;
  long long max,min,ans;
  scanf("%lld%lld%lld",&N,&A,&B);
  if(A > B){
    ans = 0;
  }else if(N == 1 && A != B){
    ans = 0;
  }else{
    min = A*(N-1)+B;
    max = B*(N-1)+A;
    ans = max-min+1;
  }
  printf("%lld\n",ans);
  return 0;
}