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.
if __name__== "__main__":
    inp=(input()).split(" ")
    n=int(inp[0])
    a=int(inp[1])
    b=int(inp[2])
    s=0
    i=a+1
    while i<=n:
        if (b>=(n-i)):
            s=s+1
        i=i+1
    print(s)