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.
from Queue import * # Queue, LifoQueue, PriorityQueue
from bisect import * #bisect, insort
from datetime import * 
from collections import * #deque, Counter,OrderedDict,defaultdict
#set([]) 
import calendar
import heapq
import math
import copy
import itertools
import string
myread = lambda : map(int,raw_input().split())
def solver():
    n,a,b = myread()
    print min(n-a,b+1)



if __name__ == "__main__":
    solver()
    
