#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int N=500005;
int n,a[N];
ll k,sm1,sm2;
multiset<int> s1,s2;
void mt(){
    int l=s1.size()+s2.size();
    while(s1.size()>(l+1)/2) s2.insert(*s1.rbegin()),sm2+=(*s1.rbegin()),sm1-=(*s1.rbegin()),s1.erase(prev(s1.end()));
    while(s1.size()<(l+1)/2) s1.insert(*s2.begin()),sm1+=(*s2.begin()),sm2-=(*s2.begin()),s2.erase(s2.begin());
}
void add(int x){
    if(x>=(*s2.begin())) s2.insert(x),sm2+=x;
    else s1.insert(x),sm1+=x;
    mt();
}
void del(int x){
    if(s1.count(x)) s1.erase(s1.find(x)),sm1-=x;
    else s2.erase(s2.find(x)),sm2-=x;
    mt();
}
bool chk(){
    int v=(*s1.rbegin());
    return (1ll*(s1.size())*v-sm1+sm2-1ll*(s2.size())*v)<=k;
}
void solve(){
    scanf("%d%lld",&n,&k);
    for(int i=1;i<=n;i++) scanf("%d",&a[i]),a[i]-=i;
    s1.clear(),s2.clear(),sm1=sm2=0;
    int l=1,as=0;
    for(int i=1;i<=n;i++){
        add(a[i]);
        while(!chk()) 
            del(a[l]),l++;
        as=max(i-l+1,as);
    }
    printf("%d\n",as);
}
int main(){
    int T;
    scanf("%d",&T);
    while(T--) solve();
}