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.

The only line contains three integers n, a and b (0 ≤ a, b < n ≤ 100).

Print the single number — the number of the sought positions.

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<iostream>

using namespace std;

int main()

{

    int n,a,b;

    while(cin>>n>>a>>b)

    {

        int cnt=;

        for(int i=;i<n;i++)

        {

            if(i>=a&&n-i-<=b)

                cnt++;

        }

        cout<<cnt<<endl;

    }

    return ;

}