#include<bits/stdc++.h>
#define fi first
#define se second
#define be begin()
#define pb push_back
#define rz resize
#define all(x) (x).begin(),(x).end()
#define SZ(x) ((int)x.size())
#define rep(i,a,n) for(int i=a;i<=n;i++)
#define per(i,a,n) for(int i=n;i>=a;i--)
#define IOS ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
using ll = long long;
using PII = pair<int,int>;
using pll = pair<ll,ll>;
using db = long double;
#define N int(5e5+10)
int n,k,tot;
int a[N],b[N],rt[N*20],rs[N*20],ls[N*20],num[N*20];
ll sumv[N*20];
int build(int cl,int cr)
{
    int n1=tot++;
    if(cl==cr) return n1;
    int mid=(cl+cr)>>1;
    ls[n1]=build(cl,mid), rs[n1]=build(mid+1,cr);
    return n1;
}
int update(int n2,int cl,int cr,int x)
{
    int n1=tot++;   
    num[n1]=num[n2]+1,sumv[n1]=sumv[n2]+b[x];
    ls[n1]=ls[n2],rs[n1]=rs[n2];
    if(cl==cr) return n1;
    int mid=(cl+cr)>>1;
    if(x<=mid) ls[n1]=update(ls[n2],cl,mid,x);
    else rs[n1]=update(rs[n2],mid+1,cr,x);
    return n1;
}
ll que(int n1,int n2,int cl,int cr,int x)
{
    if(cl==cr) return 1ll*b[cl]*x;
    int mid=(cl+cr)>>1;
    int k1=num[ls[n2]]-num[ls[n1]];
    if(k1>=x) return que(ls[n1],ls[n2],cl,mid,x);
    else return sumv[ls[n2]]-sumv[ls[n1]]+que(rs[n1],rs[n2],mid+1,cr,x-k1);
}
ll quei(int n1,int n2,int cl,int cr,int x)
{
    //cout<<cl<<" "<<cr<<"?";
    if(cl==cr) return b[cl];
    int mid=(cl+cr)>>1;
    int k1=num[ls[n2]]-num[ls[n1]];
    //cout<<num[rs[n2]]-num[rs[n1]]<<endl;
    if(k1>=x) return quei(ls[n1],ls[n2],cl,mid,x);
    else return quei(rs[n1],rs[n2],mid+1,cr,x-k1);
}
void solve()
{
    int p=1,ans=1;
    rep(i,1,n) a[i]=b[i]=0;
    cin>>n>>k;
    rep(i,1,n) cin>>a[i],a[i]-=i,b[i]=a[i];
    sort(b+1,b+n+1,[&](int x,int y){return x<y;});
    //rep(i,1,n) cout<<b[i]<<" ";
    int cnt=unique(b+1,b+n+1)-b-1;
    //cout<<cnt<<endl;
    rt[0]=build(1,cnt);
    rep(i,1,n)
    {
        //cout<<a[i]<<"->";
        a[i]=lower_bound(b+1,b+cnt+1,a[i])-b;
        //cout<<a[i]<<endl;
        rt[i]=update(rt[i-1],1,cnt,a[i]);
    }
    //rep(i,1,n)
    //  cout<<quei(rt[0],rt[n],1,cnt,i)<<endl;
    rep(i,1,n)
    {
        if(p<i) p=i;
        while(p<=n)
        {
            int k1=(p-i+1)/2; 
            //cout<<i<<p<<k1+1<<quei(rt[i-1],rt[p],1,cnt,k1+1)<<endl;
            ll v1=que(rt[i-1],rt[p],1,cnt,k1);
            //cout<<i<<" "<<p<<" "<<k1<<" "<<v1<<endl;
            ll v2=que(rt[i-1],rt[p],1,cnt,p-i+1)-v1;
            if(!((p-i+1)&1))
            {
                //cout<<v2<<v1<<endl;   
                if(v2-v1<=k) p++,ans=max(ans,p-i);
                else break;
            }
            else if((p-i+1)&1)
            {
                ll v3=quei(rt[i-1],rt[p],1,cnt,k1+1);
                if(v2-v1-v3<=k) p++,ans=max(ans,p-i);
                else break;
            }
        }
        if(p>n)
        {
            ans=max(ans,n-i+1);
            break;
        }
    }
    cout<<ans<<"\n";
}
int main()
{
    // freopen("input.txt","r",stdin);
    // freopen("2.txt","w",stdout);
    IOS
    int t=1; cin>>t;
    while(t--) solve();
    return 0;
}