/***始まる~***/
#include <bits/stdc++.h>
using namespace std;

#define MULTIINPUT 1

#ifdef ONLINE_JUDGE
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
#else
#include <dbg.h>
#endif

#define all(x, y) x.begin() + y, x.end()
#define mkp make_pair
#define pii pair<int, int>
#define pil pair<int, long long>
#define pli pair<long long, int>
#define pll pair<long long, long long>
#define ll long long
#define ull unsigned long long
#define pb push_back
#define rep(name, base, limit) for(int name = base; name <= limit; ++name)
#define per(name, base, limit) for(int name = base; name >= limit; --name)
#define lowbit(x) ((x) & -(x))
#define ls(p) ((p) << 1)
#define rs(p) ((p) << 1 | 1)
const int INF = 0x3f3f3f3f;
const long long LNF = 0x3f3f3f3f3f3f3f3f;

inline long long read()
{
    long long x=0,f=1;char ch=getchar();
    while (ch<'0'||ch>'9'){if (ch=='-') f=-1;ch=getchar();}
    while (ch>='0'&&ch<='9'){x=x*10+ch-48;ch=getchar();}
    return x*f;
}

struct fenwick
{
    vector<ll> tree;
    int n;
    fenwick(int _n)
    {
        n = _n;
        tree.resize(n + 1);
    }
    void update(int idx, ll w)
    {
        for (int i = idx; i <= n; i += lowbit(i)) tree[i] += w;
    }
    ll query(int idx)
    {
        ll ret = 0;
        for (int i = idx; i; i -= lowbit(i)) ret += tree[i];
        return ret;
    }
    ll query(int l, int r)
    {
        return query(r) - query(l - 1);
    }
};
void solve()
{
	int n = read();
    ll k = read();
    vector<ll> a(n + 1), v;
    rep(i, 1, n) a[i] = read() - i, v.pb(a[i]);
    ll mx = *max_element(all(a, 1)), mn = *min_element(all(a, 1));
    sort(all(v, 0));
    v.erase(unique(all(v, 0)), v.end());
    int m = v.size();
    auto find = [&](ll w)
    {
        return lower_bound(all(v, 0), w) - v.begin() + 1;
    };
    int idx = 0, ans = 1;
    fenwick trsum(m), trcnt(m);
    auto add = [&](int idx)
    {
        trsum.update(find(a[idx]), a[idx]);
        trcnt.update(find(a[idx]), 1);
    };
    auto del = [&](int idx)
    {
        trsum.update(find(a[idx]), -a[idx]);
        trcnt.update(find(a[idx]), -1);
    };
    auto cal = [&](ll w) -> ll
    {
        ll ret = 0;
        int idx = find(w);
        if (idx <= m) ret += trsum.query(idx, m) - trcnt.query(idx, m) * w;
        --idx;
        if (idx >= 1) ret += trcnt.query(1, idx) * w - trsum.query(1, idx);
        return ret; 
    };
    
    auto check = [&](int idx) -> bool
    {
        add(idx);
        ll l = mn, r = mx, ans = LNF;
        while (l + 1 < r)
        {
            ll mid = (l + r) / 2;
            ll a1 = cal(mid - 1), a2 = cal(mid + 1);
            if (a1 > a2) ans = min(ans, a1), l = mid;
            else ans = min(ans, a2), r = mid;
        }
        ans = min({ans, cal(l), cal(r)});
        if (ans > k) del(idx);
        return (ans <= k);
    };
    rep(i, 1, n)
    {
        while (idx < n && check(idx + 1)) ++idx;
        ans = max(ans, idx - i + 1);
        del(i);
    }
    cout << ans;
}

//left: mid = l + r, pass: r = mid, else: l = mid + 1
//right: mid = l + r + 1, pass: l = mid, else: r = mid - 1
//m1 = l + (r - l) / 3, m2 = r - (r - l) / 3;
//udu: cal(m1) > cal(m2) dud: cal(m1) < cal(m2)
//pass: l = m1 + 1, else: r = m2 - 1;
signed main()
{
    //std::ios::sync_with_stdio(false);
    #if MULTIINPUT
    int _t = read();
    while (_t--)
    {
        #endif
        solve();
        #if MULTIINPUT
        putchar('\n');
    }
    #endif
    return 0;
}