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;
int dX[8] = {1, 0, 0, -1, -1, -1, 1, 1};
int dY[8] = {0, 1, -1, 0, -1, 1, -1, 1};
int dx[4] = {1, 0, 0, -1};
int dy[4] = {0, 1, -1, 0};
long double EPS = 1e-9;
long long int MOD = 1e9 + 7;
const int N = 1e3 + 10, M = 1e4, OO = 0x3f3f3f3f;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  ;
  int n, a, b;
  cin >> n >> a >> b;
  int ans = 0;
  for (int i = 1; i <= n; i++) {
    if (i > a && n - i <= b) ++ans;
  }
  cout << ans << endl;
  return 0;
}
