#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
constexpr int maxn=5e5+5;
ll a[maxn];
inline void solve(){
    int n;ll k;
    cin>>n>>k;
    for(int i=1;i<=n;i++) cin>>a[i],a[i]-=i;
    multiset<int> P,Q;
    int ans=0,j=1;
    ll suml=0,sumr=0;
    for(int i=1;i<=n;i++){
        while(j<=n){
            if(!Q.empty()&&*Q.begin()<=a[j]) Q.insert(a[j]),sumr+=a[j];
            else P.insert(a[j]),suml+=a[j];
            while(P.size()>Q.size()+1){
                auto x=P.rbegin();
                suml-=*x,sumr+=*x;
                Q.insert(*x),P.erase(P.find(*x));
            }
            while(P.size()<Q.size()){
                auto x=Q.begin();
                sumr-=*x,suml+=*x;
                P.insert(*x),Q.erase(Q.find(*x));
            }
            int w=*P.rbegin();
            if(w*1ll*P.size()-suml+sumr-w*1ll*Q.size()>k) break;
            j++;
        }
        ans=max(j-i,ans);
        if(P.count(a[i])) P.erase(P.find(a[i])),suml-=a[i];
        else Q.erase(a[i]),sumr-=a[i];
    }
    cout<<ans<<'\n';
}
int main(){
    std::ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    int t;cin>>t;
    while(t--) solve();
}