#include<bits/stdc++.h>
using namespace std;
using ll=long long;
const ll inf=1e18;
void solve(){
    ll n,k;
    cin >> n >> k;
    vector<ll> a(n+1);
    for(int i=1;i<=n;++i){
        std::cin >> a[i];
        a[i]-=i;
    }
    int L=1,R=1;
    multiset<ll> s2;
    multiset<ll,greater<>> s1;
    s1.insert(-inf);
    s2.insert(inf);
    ll sum1=0,sum2=0;
    s2.insert(a[1]);
    sum2+=a[1];
    int ans=1;
    while(R<=n){
        ++R;
        if(a[R]>*s1.begin()){
            s2.insert(a[R]);
            sum2+=a[R];
        }else{
            s1.insert(a[R]);
            sum1+=a[R];
        }
        while(fabs(s1.size()-s2.size())>1){
            if(s1.size()>s2.size()){
                ll top=*s1.begin();
                sum2+=top;
                s2.insert(*s1.begin());
                s1.erase(s1.begin());
                sum1-=top;
            }
            if(s1.size()<s2.size()){
                ll top=*s2.begin();
                sum1+=top;
                s1.insert(*s2.begin());
                s2.erase(s2.begin());
                sum2-=top;
            }
        }
        while(true){
            bool f=true;
            if(s1.size()>=s2.size()){
                ll mid=*s1.begin();
                ll now=(int)s1.size()*mid-sum1;
                now+=sum2-(int)s2.size()*mid;
                if(now>k) f=false;
            }else if(s1.size()<s2.size()){
                ll mid=*s2.begin();
                ll now=(int)s1.size()*mid-sum1;
                now+=sum2-(int)s2.size()*mid;
                if(now>k) f=false;
            }
            if(f) break;
            if(a[L]>*s1.begin()){
                s2.erase(s2.find(a[L]));
                sum2-=a[L];
            }else{
                s1.erase(s1.find(a[L]));
                sum1-=a[L];
            }
            ++L;
            while(fabs(s1.size()-s2.size())>1){
                if(s1.size()>s2.size()){
                    ll top=*s1.begin();
                    sum2+=top;
                    s2.insert(*s1.begin());
                    s1.erase(s1.begin());
                    sum1-=top;
                }
                if(s1.size()<s2.size()){
                    ll top=*s2.begin();
                    sum1+=top;
                    s1.insert(*s2.begin());
                    s2.erase(s2.begin());
                    sum2-=top;
                }
            }


        }
        ans=max(ans,R-L+1);

    }
    cout<<ans<<'\n';

}

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin>>t;
    while(t--) solve();
    return 0;
}