Aggressive cow (binary serch

#include <iostream>
using namespace std;
bool check(int arr[], int n, int m, int mid)
{
    //        AGGERASIVE COW PROBLEM
    int cow = 1;
    int first_pos = arr[0];
    for (int i = 0; i < n; i++)
    {
        if (arr[i] - arr[0] >= mid)
        {
            cow++;
            if (cow == m)
            {
                return true;
            }
            first_pos = arr[i];
        }
    }
    return false;
}
int possible_min(int arr[], int n, int m)
{
    int sum = arr[n - 1] - arr[0];
    int s = 0;
    int ans = -1;
    int e = sum;
    int mid = (s + e) / 2;
    while (s <= e)
    {
        if (check(arr, n, m, mid))
        {
            ans = mid;
            s = mid + 1;
        }
        else
        {
            e = mid - 1;
        }
        mid = (s + e) / 2;
    }
    return ans;
}
int main()
{
    int n;
    int m;
    cout << "ENTER THE SIZE OF ARRAY--->";
    cin >> n;
    int arr[100];
    for (int i = 0; i < n; i++)
    {
        cin >> arr[i];
    }
    sort(arr, arr + n);
    for (int i = 0; i < n; i++)
    {
        cout << arr[i] << " ";
    }
    cout << endl;
    cout << "ENTER THE COUNT OF AGGRESIVE COW--->";
    cin >> m;
    cout << endl;

    cout << "ANSWER--->" << possible_min(arr, n, m);

    return 0;