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.

# -*- coding: utf-8 -*-
# @Date    : 2018-10-02 08:00:37
# @Author  : raj lath (oorja.halt@gmail.com)
# @Link    : link
# @Version : 1.0.0

from sys import stdin

max_val=int(10e12)
min_val=int(-10e12)

def read_int()     : return int(stdin.readline())
def read_ints()    : return [int(x) for x in stdin.readline().split()]
def read_str()     : return input()
def read_strs()    : return [x for x in stdin.readline().split()]


nb_peoples, min_ahead, max_back = read_ints()
print(min(nb_peoples - min_ahead, max_back + 1))
