output_description: Print the number of the different possible sums.
  
  * * *
input_description: Input is given from Standard Input in the following format:
  
      
      
      N A B
attempt: N,A,B = map(int,input().split())
  check = B - A + 1
  loop = N - 2
  if check < loop:
    loop = check
  if B < A or (N == 1 and A != B):
    print(0)
    exit(0)
  elif N == 1　or N ==2:
    print(1)
    exit(0)
  
  if loop % 2 == 0:
    ans = (check + check - loop +1)*(loop/2)
  elif loop % 2 == 1:
    ans = (check + check - loop+1)*((loop-1)/2)+check -(loop -1)/2
    
  print(int(ans))
  
problem_description: 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?
samples: [{"input": "4 4 6", "output": "5\n    \n\nThere are five possible sums: 18=4+4+4+6, 19=4+4+5+6, 20=4+5+5+6, 21=4+5+6+6\nand 22=4+6+6+6.\n\n* * *"}, {"input": "5 4 3", "output": "0\n    \n\n* * *"}, {"input": "1 7 10", "output": "0\n    \n\n* * *"}, {"input": "1 3 3", "output": "1"}]