#include<bits/stdc++.h>

using namespace std;
#define fast ios_base::sync_with_stdio(false);cin.tie(NULL)
int t;
long long n, k;
vector<long long> v;

bool check(long long num) {
    for (int i = 0; i < n; i++) {
        vector<long long> v_c(v.begin(), v.end());
        long long charge = k;
        long long nn = num;
        v_c[i] = nn;
        for (int j = i; j < n; j++) {
            if (v_c[j] <= v[j])return true;
            if (j + 1 < n)v_c[j + 1] = v_c[j] - 1;
            charge -= (v_c[j] - v[j]);
            if (charge < 0)break;
        }
    }
    return false;
}

int main() {
    fast;
    cin >> t;
    while (t--) {
        cin >> n >> k;
        v.resize(n);
        for (auto &ele: v)cin >> ele;
        long long l = 1, r = 1e9;
        long long ans = 0;
        while (l <= r) {
            long long mid = (l + r) / 2;
            if (!check(mid))r = mid - 1;
            else ans = mid, l = mid + 1;
        }
        cout << ans << endl;
    }
    return 0;
}