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 modpow(long long a, long long b) {
  long long r = 1;
  while (b > 0) {
    if (b & 1) r = (r * a);
    a = (a * a);
    b >>= 1;
  }
  return r;
}
bool sortbysec(const pair<int, int> &a, const pair<int, int> &b) {
  return (a.first > b.first);
}
int main() {
  long long t, i, j, k, l, m, n, a, b;
  long long cnt = 0;
  cin >> n >> a >> b;
  for (i = n; i >= 1; i--) {
    if (n - i <= b && i - 1 >= a) cnt++;
  }
  cout << cnt << endl;
}
