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: import combinations from itertools
  n = [int(i) for i in input().split()]
  if n[0] == 1 and n[1] < n[2]:
      print(0)
  elif n[1]>n[2]:
      print(0)
  elif n[0] == 1 and n[1]==n[2]:
      print(1)
  else:
      m = range(n[1],n[2]+1)
      c = list(combinations(m,n[0]-2))
      c.extend([(i,i) for i in m])
      print(len(set([i+j for i,j in c])))
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"}]