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.
"""""""""""""""""""""""""""""""""""""""""""""
|    author: mr.math - Hakimov Rahimjon     |
|    e-mail: mr.math0777@gmail.com          |
"""""""""""""""""""""""""""""""""""""""""""""
#inp = open("lepus.in", "r"); input = inp.readline; out = open("lepus.out", "w"); print = out.write
TN = 1


# ===========================================

  
def solution():
    n, a, b = map(int, input().split())
    ans = 0
    for j in range(a, n+1):
        if 0<=n-j-1<=b:
            ans += 1
    print(ans)


# ===========================================
while TN != 0:
    solution()
    TN -= 1
# ===========================================
#inp.close()
#out.close()