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.
#include <bits/stdc++.h>
using namespace std;
const int CMax = 1000002;
const int CVMax = 102;
const int CInf = 2000000001;
const long long CMod = 1000000007;
int n;
int A[CMax];
long long gcd(long long a, long long b) {
  if (b != 0)
    return gcd(b, a % b);
  else
    return a;
}
int main() {
  int a, b, tmp, res = 1, tmp1;
  scanf("%d %d %d", &n, &a, &b);
  tmp = max(a, n - b - 1);
  printf("%d\n", n - tmp);
  return 0;
}
