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;
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long poww(long long a, int b) {
  long long ans = 1;
  for (int i = 1; i <= b; i++) ans *= a;
  return ans;
}
vector<pair<int, int> > v;
int main() {
  int n, a, b, rem, ans = 0;
  cin >> n >> a >> b;
  rem = n - a;
  if ((a + b) < n) b++;
  ans = min(rem, b);
  cout << ans;
  return 0;
}
