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.
import os
import sys
from sys import stdin, stdout
from io import BytesIO, IOBase
# from itertools import permutations, combinations, accumulate
# from math import sqrt, gcd, floor, ceil, log2
mod = int(1e9)+7

intn = lambda : int(stdin.readline())
strs = lambda : stdin.readline()[:-1]
lstr = lambda : list(stdin.readline()[:-1])
mint = lambda : map(int, stdin.readline().split())
lint = lambda : list(map(int, stdin.readline().split()))
out = lambda x: stdout.write(str(x)+"\n")
out_ = lambda x: stdout.write(str(x)+" ")

def main():
    n,a,b = mint()
    out(min(n-a, b+1))

if __name__ == "__main__":
    main()