#include <bits/stdc++.h>
using namespace std;
#define LL long long
#define ULL unsigned long long
#define Enter putchar('\n')
#define spc putchar(' ')
#define pb push_back
#define fi first
#define se second
inline void read(int &num){num=0;int f=1;char ch=getchar();while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){num=(num<<1)+(num<<3)+(ch^48);ch=getchar();}num*=f;}
inline void lread(long long &num){num=0;int f=1;char ch=getchar();while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){num=(num<<1)+(num<<3)+(ch^48);ch=getchar();}num*=f;}
void print(long long num){if(num<0){putchar('-');num=-num;}if(num>9){print(num/10);}putchar((num%10)^48);}
LL a[500009],sd,sx;
bool cmp1(const int &num1,const int &num2){
    return a[num1]<a[num2];
}
bool cmp2(const int &num1,const int &num2){
    return a[num1]>a[num2];
}
multiset<int,bool(*)(const int &,const int &)> d(cmp1);
multiset<int,bool(*)(const int &,const int &)> x(cmp2);
void bal();
void plu(int y){
    if(a[*x.begin()]>=a[y]){
        x.insert(y);
        sx+=a[y];
    }
    else{
        d.insert(y);
        sd+=a[y];
    }
    bal();
}
void mus(int y){
    auto it=d.find(y);
    if(it==d.end()){
        it=x.find(y);
        sx-=a[y];
        x.erase(it);
    }
    else{
        sd-=a[y];
        d.erase(it);
    }
    bal();
}
void bal(){
    while(d.size()>x.size()){
        int y=*d.begin();
        sd-=a[y];
        sx+=a[y];
        x.insert(y);
        d.erase(d.begin());
    }
    while(x.size()-d.size()>1){
        int y=*x.begin();
        sx-=a[y];
        sd+=a[y];
        d.insert(y);
        x.erase(x.begin());
    }
}
int main(){
    int T,n;
    LL k;
    read(T);
    while(T--){
        read(n),lread(k);
        d.clear(),x.clear();
        for(int i=1;i<=n;i++){
            lread(a[i]);
            a[i]-=i;
        }
        int l=1,r=1,ans=1;
        LL re,t;
        sd=0,sx=a[1];
        x.insert(1);
        while(1){
            re=*x.begin();
            t=a[re]*(x.size()-d.size())-sx+sd;
            //cout<<re<<' '<<x.size()<<' '<<d.size()<<' '<<sx<<' '<<sd<<endl;
            if(t<=k){
                //cout<<l<<' '<<r<<endl;
                ans=max(ans,r-l+1);
                ++r;
                if(r>n)break;
                plu(r);
            }
            else{
                mus(l);
                ++l;
            }
        }
        print(ans),Enter;
    }
    return 0;
}
/*
1
5 6
1 1 1 1 1
*/