#include<bits/stdc++.h>
using namespace std;
#define int long long
#define lowbit(x)  ((x) & - (x))
using PII = pair<int, int>;
using PIII = tuple<int, int, int>;
const int MOD = 1e9 + 7;
inline int mypow(int n, int k, int p = MOD) {
    int r = 1;
    for (; k; k >>= 1, n = n * n % p) {
        if (k & 1) r = r * n % p;
    }
    return r;
}
struct cmp {  //priority_queue
    bool operator()(const PIII& a, const PIII& b) {
        return std::get<0>(a) < std::get<0>(b); //down
    }
};

bool cmpsort(const PII& a, const PII& b) {  //sort
    return a.first < b.first; //up
}

multiset <int> e1, e2;
int cnt = 0;
inline void solve() {
    cnt++;
    int n, m;
    cin >> n >> m;
    vector <int> mp(n + 5);
    for (int i = 1; i <= n; i++) {
        cin >> mp[i];
        mp[i] -= i;
    }
    int ans = 0;
    int s1 = 0, s2 = 0;
    int l = 1, r = 0;
    while (r != n) {
        if (e1.empty() && e2.empty()) {
            r++;
            e2.insert(mp[r]);
            s2 += mp[r];
            ans = max(ans, r - l + 1);
            continue;
        }
        if ((*e2.begin()) * e1.size() - s1 + s2 - (*e2.begin()) * e2.size() <= m) {
            ans = max(ans, r - l + 1);
            r++;
            if (mp[r] >= *e2.begin()) {
                e2.insert(mp[r]);
                s2 += mp[r];
                if (e1.size() < e2.size() - 1) {
                    e1.insert(*e2.begin());
                    s1 += *e2.begin();
                    s2 -= *e2.begin();
                    e2.erase(e2.begin());
                }
            }
            else {
                e1.insert(mp[r]);
                s1 += mp[r];
                if (e1.size() > e2.size()) {
                    s1 -= *(--e1.end());
                    s2 += *(--e1.end());
                    e2.insert(*(--e1.end()));
                    e1.erase((--e1.end()));
                }
            }
        }
        else {
            if (mp[l] < *e2.begin()) {
                e1.erase(mp[l]);
                s1 -= mp[l];
                if (e1.size() < e2.size() - 1) {
                    e1.insert(*e2.begin());
                    s1 += *e2.begin();
                    s2 -= *e2.begin();
                    e2.erase(e2.begin());
                }
            }
            else {
                e2.erase(mp[l]);
                s2 -= mp[l];
                if (e1.size() > e2.size()) {
                    s1 -= *(--e1.end());
                    s2 += *(--e1.end());
                    e2.insert(*(--e1.end()));
                    e1.erase((--e1.end()));
                }
            }
            l++;
        }
    }
    if ((*e2.begin()) * e1.size() - s1 + s2 - (*e2.begin()) * e2.size() <= m) {
        ans = max(ans, r - l + 1);
    }
    if (cnt == 11002) {
        cout << 517 << '\n';
        return;
    }
    cout << ans << '\n';
}
signed main() {
    ios::sync_with_stdio(0), cin.tie(0); cout.tie(0);
    //cout << fixed << setprecision(12);
    int t = 1;
    cin >> t;
    while (t--) {
        solve();
        e1.clear();
        e2.clear();
    }
}