#include <bits/stdc++.h>
#define maxn 500100
#define int long long
typedef __int128_t int128;
using namespace std;
const double eps=1e-8;
int a[maxn];
void solve(){
    multiset<int>res1,res2;
    int n,k,sum1=0,sum2=0,ans=0;
    cin >> n >> k;
    for(int i=1;i<=n;++i)  cin >> a[i],a[i]-=i;
    int l=1,r=1;  sum1+=a[r];  res1.emplace(a[r]);
    while(r<=n){
        int cur=*(res1.begin()),sz1=res1.size(),sz2=res2.size();
        int tmp=(sum1-sz1*cur)+(sz2*cur-sum2);
        if(tmp<=k){
            ans=max(ans,r-l+1);  ++r;
            if(r>n)  break;
            if(a[r]>=cur)  res1.emplace(a[r]),sum1+=a[r];
            else  res2.emplace(a[r]),sum2+=a[r];
        }
        else{
            int qq=a[l++];
            if(res1.find(qq)!=res1.end())  res1.erase(res1.find(qq)),sum1-=qq;
            else if(res2.find(qq)!=res2.end())  res2.erase(res2.find(qq)),sum2-=qq;
        }
        if(res1.size()>res2.size()+1){
            int tt=*(res1.begin());
            res1.erase(res1.find(tt));  sum1-=tt;
            res2.emplace(tt);  sum2+=tt;
        }
        else if(res2.size()>res1.size()){
            int tt=*(--res2.end());
            res2.erase(res2.find(tt));  sum2-=tt;
            res1.emplace(tt);  sum1+=tt;
        }
    }
    cout << ans << '\n';
}
signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);cout.tie(0);
    int t; cin >> t;
    while(t--){
        solve();
    }
    return 0;
}