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())
print(min(b+1,n-a))

#n-a to remove initial element
#b+1 for no more than b
#see.....more than b means b+1,b+2,b+3.....and no more than b means 0,1,2....b.
#therefore we have b+1 elements 
#now for finla answer we are taking intersection
#basically finding common elements that satisfy both equations
#suppose 9 1 3
#in this case 2,3,4,5 will not be intersectng elements as they are no more than 3.
#starting 1 element in first condition
#last 4 elements in second condition
#so we have to ignore elements in between