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.
n,a,b=map(int,input().split())
l1,l2=[],[]
for i in range(1,n+1):
    if((i-1)>=a):
        l1.append(i)
for i in range(1,n+1):
    if((n-i)<=b):
        l2.append(i)
def common_member(a, b):
    a_set = set(a)
    b_set = set(b)
    if (a_set & b_set):
        print(len(a_set & b_set))
common_member(l1,l2)


