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#include <bits/stdc++.h>

using namespace std;
#define ll long long
#define speed ios_base::sync_with_stdio(false);cin.tie(0), cout.tie(0);

/*
                    " وَأَن لَّيْسَ لِلْإِنسَانِ إِلَّا مَا سَعَى ﴿39﴾ وَأَنَّ سَعْيَهُ سَوْفَ يُرَى ﴿40﴾ ثُمَّ يُجْزَاهُ الْجَزَاء الْأَوْفَى "
*/
const ll inf = 1e18;

bool valid(ll h, vector<ll> &v, ll &x) {
    ll w = 0;
    for (int i = 0; i < v.size(); i++) {
        if (h >= v[i]) {
            w += h - v[i];
        }
    }
    return w <= x;
}

void solve() {
    ll n, x;
    cin >> n >> x;
    vector<ll> v(n);
    for (int i = 0; i < n; i++) {
        cin >> v[i];
    }
    ll l = 1, r = 1e12, mid, ans = -1;
    while (l <= r) {
        mid = (l + r) / 2;
        if (valid(mid, v, x)) {
            ans = mid;
            l = mid + 1;
        } else {
            r = mid - 1;
        }
    }
    cout << ans << "\n";
}

int main() {
    speed
    int testcases = 1;
    cin >> testcases;
    while (testcases--)
        solve();
}