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>
#include <math.h>
//1.判断数据是否合理 2. 计算结果
int main()
{
   long int  n,k,t,min,max;
  scanf("%ld %ld %ld",&n,&k,&t);
  if(n<1||k>1e9||t>1e9||n>1e9)
  {
     printf("0\n");
      return 0;
  }
 if(k>=t||(n==1&&k!=0&&t!=0))
 {
     printf("0\n");
     return 0;
 }

  max=(n-1)*t+k;
  min =(n-1)*k+t;
  printf("%ld\n",max-min+1);
    return 0;
}