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 N = 100001;
int mod = 1e9 + 7;
int min(int a, int b) {
  if (a < b)
    return a;
  else
    return b;
}
int max(int a, int b) {
  if (a > b)
    return a;
  else
    return b;
}
int power(int a, int b) {
  int res = 1;
  a %= mod;
  assert(b >= 0);
  for (; b; b >>= 1) {
    if (b & 1) res = res * a % mod;
    a = a * a % mod;
  }
  return res;
}
int gcd(int p, int q) {
  if (p % q == 0)
    return q;
  else {
    return gcd(q, p % q);
  }
}
bool comp(int a, int b) { return (a > b); }
void solve() {
  int n, a, b;
  cin >> n >> a >> b;
  cout << n - max(a + 1, n - b) + 1;
}
int main() {
  solve();
  return 0;
}
