#include <bits/stdc++.h>
using namespace std;
using ull=unsigned long long;
using ll=long long;
ll tr[500010][2];
int n,k;
vector<int> ve;
int get(int x){
    return lower_bound(ve.begin(),ve.end(),x)-ve.begin()+1;
}
int sz;
void add(int x,int t,int num){
    for(;x<=sz;x+=x&-x) tr[x][t]+=num;
}
ll get_pre_sum(int len){
    ll sum=0;int p=0;
    for(int i=20;i>=0;i--){
        if(p+(1<<i)>sz) continue;
        if(len>tr[p+(1<<i)][0]){
            len-=tr[p+(1<<i)][0];
            sum+=tr[p+(1<<i)][1];
            p+=(1<<i);
        }
    }
    if(len>0)   sum+=1ll*ve[p]*len;
    return sum;
}
ll get_ope(int len){
    if(len&1){
        ll sum_1=get_pre_sum(len/2);
        ll sum_2=get_pre_sum(len/2+1);
        //cout<<sum_1<<' '<<sum_2<<'\n';
        return get_pre_sum(len)-sum_2-sum_1;
    }
    else{
        ll sum_1=get_pre_sum(len/2);
        ll sum_2=get_pre_sum(len);
        return sum_2-2*sum_1;   
    }
}
int a[500010];
void solve() {
    cin>>n>>k;
    int num;
    ve.clear();
    for(int i=1;i<=n;i++){
        cin>>num;
        num-=i;
        a[i]=num;
        ve.push_back(num);
    }
    sort(ve.begin(),ve.end());
    ve.erase(unique(ve.begin(),ve.end()),ve.end());
    sz=ve.size();
    for(int i=0;i<=sz;i++)  tr[i][0]=tr[i][1]=0;
    int le=1,re=0;
    int ans=0;
    while(re<n){
        re++;
        int wei=get(a[re]);
        add(wei,0,1);
        add(wei,1,a[re]);
        while(get_ope(re-le+1)>k){
            //cout<<le<<' '<<re<<' '<<get_pre_sum(re-le+1)<<'\n';
            wei=get(a[le]);
            add(wei,0,-1);
            add(wei,1,-a[le]);
            le++;
        }
        ans=max(ans,re-le+1);
    }
    cout<<ans<<'\n';
}
int main() {
    ios::sync_with_stdio(0),cin.tie(0);
    int _ = 1;
    cin >> _;
    while(_--) solve();
    return 0;
}