Petr stands in line of n people, but he doesn't know exactly which position he occupies. He can say that there are no less than a people standing in front of him and no more than b people standing behind him. Find the number of different positions Petr can occupy.

Input

The only line contains three integers n, a and b (0 ≤ a, b < n ≤ 100).

Output

Print the single number — the number of the sought positions.

Examples

Input

3 1 1


Output

2


Input

5 2 3


Output

3

Note

The possible positions in the first sample are: 2 and 3 (if we number the positions starting with 1).

In the second sample they are 3, 4 and 5.

def main():
  a = list( input().split())
  n = int(a[0])
  x = int(a[1])
  y = int(a[2])
  #
  cnt = 0
  for i in range(1, n+1) :
    if (i-1) >= x and (n-i) <= y:
      cnt += 1
  print(cnt)
if __name__ == "__main__": main()