#include<bits/stdc++.h>
#define rep(i,x,y) for(int i=x;i<=y;i++)
#define dwn(i,x,y) for(int i=x;i>=y;i--)
#define ll long long
using namespace std;
template<typename T>inline void qr(T &x){
    x=0;int f=0;char s=getchar();
    while(!isdigit(s))f|=s=='-',s=getchar();
    while(isdigit(s))x=x*10+s-48,s=getchar();
    x=f?-x:x;
}
int cc=0,buf[31];
template<typename T>inline void qw(T x){
    if(x<0)putchar('-'),x=-x;
    do{buf[++cc]=int(x%10);x/=10;}while(x);
    while(cc)putchar(buf[cc--]+'0');
}
const int N=5e5+10;
int n,k,a[N];
multiset<int>s1,s2;//s1.size()>=s2.size()
multiset<int>::iterator it;
ll sum1,sum2;
int mid;
void push(int x){
    if(!s1.size()){
        s1.insert(x);
        sum1+=x;
        mid=x;
    }
    else if(s1.size()==s2.size()){
        int y=*s2.begin();
        if(x<=y){
            s1.insert(x);
            sum1+=x;
            mid=*(--s1.end());
        }
        else{
            s2.erase(s2.begin());sum2-=y;
            s1.insert(y);sum1+=y;mid=y;
            s2.insert(x);sum2+=x;
        }
    }
    else{
        if(x>=mid){
            s2.insert(x);sum2+=x;
        }
        else{
            s1.erase(--s1.end());sum1-=mid;
            s2.insert(mid);sum2+=mid;
            s1.insert(x);sum1+=x;
            mid=*(--s1.end());
        }
    }
}
void del(int x){
    it=s1.find(x);
    if(it!=s1.end()){
        s1.erase(it);
        sum1-=x;
    }
    else{
        s2.erase(s2.find(x));
        sum2-=x;
    }
    while(s1.size()<s2.size()){
        int x=*s2.begin();
        s2.erase(s2.begin());sum2-=x;
        s1.insert(x);sum1+=x;
    }
    if(!s1.size())mid=-1;
    else mid=*(--s1.end());
}
ll calc(){
    return (sum2-1ll*mid*s2.size())+(1ll*mid*s1.size()-sum1);
}
void init(){
    s1.clear();
    s2.clear();
    sum1=sum2=0;
    mid=-1;
}
void solve(){
    qr(n),qr(k);
    rep(i,1,n){
        qr(a[i]);
        a[i]-=i;
    }
    init();
    int ans=0,r=0;
    rep(l,1,n){
        while(r<n){
            push(a[r+1]);
            if(calc()<=k)r++;
            else{
                del(a[r+1]);
                break;
            }
        }
        // cout<<l<<" "<<r<<endl;
        // cout<<mid<<" "<<sum1<<" "<<sum2<<" "<<s1.size()<<" "<<s2.size()<<endl;
        ans=max(ans,r-l+1);
        if(r==n)break;
        del(a[l]);
        // cout<<mid<<" "<<sum1<<" "<<sum2<<" "<<s1.size()<<" "<<s2.size()<<endl;
    }
    cout<<ans<<endl;
}
int main(){
    int tt;qr(tt);
    while(tt--)solve();
    return 0;
}