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.
import sys

def readints() :
    l = sys.stdin.readline()
    return map(int, l.split(' '))

def readstring() :
    l = sys.stdin.readline()[:-1]
    return l

def readint() :
    l = sys.stdin.readline()
    return int(l)

def clearchars(s, chars) :
    for c in chars :
        s = s.replace(c, '')
    return s

def gcd(a, b) :
    if (a < b ) :
        a, b = b, a
    if b == 0 :
        return a
    return gcd(b, a % b)

n, a, b = readints()

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