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.
"""
3 1 1
no less than a standing infront
no more than b people standing behind
"""
num1 = input()
a = []


def get_the_data(count, num, arr):
    for i in range(0, len(num)):
        if num[i] == ' ':
            arr.append(int(num[count:i]))
            count = i+1
        elif i == len(num)-1:
            arr.append(int(num[count:len(num)]))
    return arr


arr1 = get_the_data(0, num1,  a)

peoples = arr1[0]
front = arr1[1]
behind = arr1[2]
places_to_take = behind + 1
check = False
while check is False:
    if  peoples - places_to_take < front :
        places_to_take -= 1
    else:
        break
print(places_to_take)