#include<iostream>
#include<algorithm>
#include<cstring>
#include<queue>

using namespace std;

typedef long long ll;

const int N = 500010;

int n;
ll k;
int a[N];

struct Heap{
    priority_queue<int> Q, E;

    void insert(int x) { Q.push(x); }
    
    void erase(int x) { E.push(x); }
    
    int top(){
        while (E.size() && Q.top() == E.top()) Q.pop(), E.pop();
        return Q.size() ? Q.top() : -0x3f3f3f3f;
    }
    
    void pop(){
        while (E.size() && Q.top() == E.top()) Q.pop(), E.pop();
        if (Q.size()) Q.pop();
    }
    
    int size() { return Q.size() - E.size(); }
};

void solve(){
    scanf("%d%lld", &n, &k);
    for (int i = 1; i <= n; i ++ ) scanf("%d", a + i);
    for (int i = 1; i <= n; i ++ ) a[i] -= i;

    ll s1 = 0, s2 = 0;
    Heap q1, q2;
    int ans = 0;

    auto adjust = [&](){
        while (q1.size() > q2.size() + 1){
            int t = q1.top();
            q1.erase(t), q2.insert(-t);
            s1 -= t, s2 += t;
        }
        while (q1.size() < q2.size()){
            int t = -q2.top();
            q1.insert(t), q2.erase(-t);
            s1 += t, s2 -= t;
        }
    };

    for (int l = 1, r = 1; r <= n; r ++ ){
        if (q1.size() == 0 || a[r] > q1.top()) q2.insert(-a[r]), s2 += a[r];
        else q1.insert(a[r]), s1 += a[r];
        adjust();
        ll mid = q1.top(), tmp = mid * q1.size() - s1 + s2 - mid * q2.size();
        if (a[r] == -1)
            a[r] = -1;
        while (tmp > k && l < r){
            if (a[l] > q1.top()) q2.erase(-a[l]), s2 -= a[l];
            else q1.erase(a[l]), s1 -= a[l];
            adjust();
            l++;
            q1.top(), tmp = mid * q1.size() - s1 + s2 - mid * q2.size();
        }
        ans = max(ans, r - l + 1);
        adjust();
    }

    printf("%d\n", ans);
}

int main(){
    int _;
    scanf("%d", &_);
    while (_ -- ) solve();
}