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 sys
import math
input = sys.stdin.readline

def int_array():
    return list(map(int, input().strip().split()))


def str_array():
    return input().strip().split()

######################## TEMPLATE ENDS HERE ########################
n,a,b = int_array()
ans = 0
for i in range(1,n+1):
    front = i - 1
    back = n - i

    if front >= a and back <= b:
        ans += 1

print(ans)