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.
nab = list(map(int, input().split()))
n = nab[0]
a = nab[1]
b = nab[2]
# a is minimum in front
# b is maximum in back
rem = n - a
posavail = [i for i in range(rem)]
cnt = 0
for i in range(len(posavail)):
    imin = i
    # print(imin, " ", len(posavail[imin + 1:]))
    if len(posavail[imin:]) - 1 <= b:
        cnt += 1
print(cnt)
