求大佬们看看，wa3个

#include <iostream>
#include <algorithm>
typedef long long ll;
using namespace std;
const int N = 3e6 + 10;
int a[N];
ll sum,n,m;

int mat(ll mid)
{
    ll sum=0;
    for (int i = 1; i <= n; i++)
    {
        if (a[i] - mid > 0)
            sum += a[i] - mid;
    }
    return sum;
}

int find(ll x)
{
    ll l = 0, r = a[n] + 1;
    while (l < r)
    {
        ll mid = r + l + 1>> 1;
        if (mat(mid) >= m)
            l = mid;
        else
            r = mid - 1;
    }
    return l;
}

int main()
{

    cin >> n >> m;
    for (int i = 1; i <= n; i++)
        cin >> a[i];
    sort(a + 1, a + n + 1);
    cout << find(m);

    return 0;
}