#include <bits/stdc++.h>
int N, A, B;
int count;
int main() {
  scanf("%d%d%d", &N, &A, &B);
  for (int i = A + 1; i <= N; i++) {
    if (N - i <= B) count++;
  }
  printf("%d\n", count);
  scanf(" ");
}

### Prompt

Please formulate a CPP solution to the following problem:

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.

### Response

```cpp
#include <bits/stdc++.h>
int N, A, B;
int count;
int main() {
  scanf("%d%d%d", &N, &A, &B);
  for (int i = A + 1; i <= N; i++) {
    if (N - i <= B) count++;
  }
  printf("%d\n", count);
  scanf(" ");
}

```