#include<iostream>
#include<algorithm>
#include<set>
using ll=long long;
const int sz=5e5+10;
int a[sz];
int main(){
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int t;
    std::cin>>t;
    while(t--)[](){
        int n;
        ll k;
        std::cin>>n>>k;
        for(int i=1;i<=n;i++)std::cin>>a[i],a[i]-=i;
        std::multiset<ll>ls,rs;
        ll res=0;
        auto add=[&](ll x){
            if(ls.empty()||x>*ls.rbegin()){
                rs.insert(x),res+=x;
                while(ls.size()+1<=rs.size()){
                    int t=*rs.begin();
                    ls.insert(t),res-=2*t;
                    rs.erase(rs.begin());
                }
            }else{
                ls.insert(x),res-=x;
                while(ls.size()-rs.size()>1){
                    ll t=*ls.rbegin();
                    rs.insert(t),res+=2*t;
                    ls.erase(--ls.end());
                }
            }
            return *ls.rbegin();
        };
        auto del=[&](ll x){
            if(rs.empty()||x<*rs.begin()){
                ls.erase(ls.find(x)),res+=x;
                while(ls.size()+1<=rs.size()){
                    ll t=*rs.begin();
                    ls.insert(t),res-=2*t;
                    rs.erase(rs.begin());
                }
            }else{
                rs.erase(rs.find(x)),res-=x;
                while(ls.size()-rs.size()>1){
                    ll t=*ls.rbegin();
                    rs.insert(t),res+=2*t;
                    ls.erase(--ls.end());
                }
            }
        };
        int ans=0;
        ll mid;
        for(int l=1,r=1;l<=n;l++){
            r=std::max(l,r);
            while(r<=n&&(mid=add(a[r]),res+(ll)ls.size()*mid-(ll)rs.size()*mid<=k))++r;
            del(a[l]),ans=std::max(ans,r-l);
        }
        std::cout<<ans<<"\n";
    }();
    return 0;
}