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.
The only line contains three integers *n*, *a* and *b* (0 ≤ *a*, *b* &lt; *n* ≤ 100).
3 1 1
2
5 2 3
3
5 4 0
1
6 5 5
1
9 4 3
4
11 4 6
7
13 8 7
5
14 5 5
6
16 6 9
10
20 13 17
7
22 4 8
9
23 8 14
15
26 18 22
8
28 6 1
2
29 5 23
24
32 27 15
5
33 11 5
6
37 21 15
16
39 34 33
5
41 27 11
12
42 25 16
17
45 7 43
38
47 16 17
18
49 11 37
38
51 38 39
13
52 29 7
8
56 43 12
13
58 57 28
1
59 12 39
40
62 9 52
53
63 29 44
34
65 30 22
23
66 27 38
39
71 33 53
38
73 14 12
13
73 37 35
36
76 69 44
7
79 25 20
21
81 60 20
21
81 79 14
2
84 0 42
43
88 79 8
9
90 76 59
14
92 2 22
23
94 5 88
89
94 62 48
32
96 22 72
73
100 11 88
89
100 81 91
19
1 0 0
1
import sys
import os
from collections import Counter, defaultdict, deque
from heapq import heapify, heappush, heappop
from functools import lru_cache
from math import floor, ceil, sqrt, gcd
from string import ascii_lowercase
from bisect import bisect_left, bisect, bisect_right


def __perform_setup__():
    INPUT_FILE_PATH = "./code/input.txt"
    OUTPUT_FILE_PATH = "./code/output.txt"

    sys.stdin = open(INPUT_FILE_PATH, 'r')
    sys.stdout = open(OUTPUT_FILE_PATH, 'w')


if "MY_COMPETITIVE_PROGRAMMING_VARIABLE" in os.environ:
    __perform_setup__()


def read():
    return input().strip()


def read_int():
    return int(read())


def read_str_list():
    return read().split()


def read_numeric_list():
    return list(map(int, read_str_list()))


def solve(N, A, B):
    ans = 0
    for i in range(N):
        people_on_left = i
        people_on_right = N-i-1

        if people_on_left >= A and people_on_right <= B:
            ans += 1

    return ans


N, A, B = read_numeric_list()

print(solve(N, A, B))
