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.
# python3
import sys, threading, os.path
import collections, heapq, math,bisect
import string
from platform import python_version
import itertools
sys.setrecursionlimit(10**6)
threading.stack_size(2**27)

def main():
    if os.path.exists('input.txt'):
        input = open('input.txt', 'r')
    else:
        input = sys.stdin
    #--------------------------------INPUT---------------------------------
    lis = list(map(int, input.readline().split()))
    output =  lis[0] - max(lis[1] + 1, lis[0] - lis[2]) + 1
    #-------------------------------OUTPUT----------------------------------
    if os.path.exists('output.txt'):
        open('output.txt', 'w').writelines(str(output))
    else:
        sys.stdout.write(str(output))


if __name__ == '__main__':
    main()
#threading.Thread(target=main).start()