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.
n1, a1, b2 = input().split()
n = int(n1)
a = int(a1)
b = int(b2)
su = 0
list1 = list(range(a,n))
list2 = list(range(0,b+1))
for val in list1:
    for val1 in list2:
        if val + val1 ==n-1:
            su = su +1
print(su)   