#include <bits/stdc++.h>
#define inf 1000000007
#define mod 1000000007
#define lson (p<<1)
#define rson (p<<1|1)
// #define int long long
// #pragma GCC optimize("Ofast","inline","-ffast-math")
// #pragma GCC target("avx,sse2,sse3,sse4,mmx")
using namespace std;
template <typename T> void read(T &x){
	x=0;char ch=getchar();int fh=1;
	while (ch<'0'||ch>'9'){if (ch=='-')fh=-1;ch=getchar();}
	while (ch>='0'&&ch<='9')x=x*10+ch-'0',ch=getchar();
	x*=fh;
}
template <typename T> void write(T x) {
	if (x<0) x=-x,putchar('-');
	if (x>9) write(x/10);
	putchar(x%10+'0');
}
template <typename T> void writeln(T x) {
	write(x);
	puts("");
}
int n,ans;
long long k;
int a[500005];
vector<int> nums;
int cnt[2000005];
long long sum[2000005];
void pushup(int p)
{
	sum[p]=sum[lson]+sum[rson];
	cnt[p]=cnt[lson]+cnt[rson];
}
void build(int p,int l,int r)
{
	sum[p]=cnt[p]=0;
	if(l==r) return;
	int mid=l+r>>1;
	build(lson,l,mid);
	build(rson,mid+1,r);
	pushup(p);
}
void modify(int p,int l,int r,int x,int v)
{
	if(l==r)
	{
		sum[p]+=1ll*v*nums[x-1];
		cnt[p]+=v;
		return;
	}
	int mid=l+r>>1;
	if(x<=mid) modify(lson,l,mid,x,v);
	else modify(rson,mid+1,r,x,v);
	pushup(p);
}
int querykth(int p,int l,int r,int k)
{
	if(l==r) return l;
	int mid=l+r>>1;
	if(cnt[lson]>=k) return querykth(lson,l,mid,k);
	else return querykth(rson,mid+1,r,k-cnt[lson]);
}
long long queryksum(int p,int l,int r,int k)
{
	if(l==r) return 1ll*k*nums[l-1];
	int mid=l+r>>1;
	if(cnt[lson]>=k) return queryksum(lson,l,mid,k);
	else return sum[lson]+queryksum(rson,mid+1,r,k-cnt[lson]);
}
long long calc()
{
	int c=cnt[1];
	if(c<=1) return 0;
	// c/2 c-c/2
	int tmp1=querykth(1,1,nums.size(),c/2+1);
	long long tmp2=queryksum(1,1,nums.size(),c/2);
	return sum[1]-tmp2-1ll*(c-c/2)*nums[tmp1-1]+1ll*(c/2)*nums[tmp1-1]-tmp2;
}
signed main()
{
	// freopen(".in","r",stdin);
	// freopen(".out","w",stdout);
	int tc;read(tc);
	while(tc--)
	{
		read(n);read(k);ans=0;
		for(int i=1;i<=n;++i)
			read(a[i]),a[i]-=i;
		nums.clear();
		for(int i=1;i<=n;++i)
			nums.push_back(a[i]);
		sort(nums.begin(),nums.end());
		nums.erase(unique(nums.begin(),nums.end()),nums.end());
		for(int i=1;i<=n;++i)
			a[i]=lower_bound(nums.begin(),nums.end(),a[i])-nums.begin()+1;
		build(1,1,nums.size());
		for(int i=1,j=0;i<=n;++i)
		{
			while(j<n&&calc()<=k) modify(1,1,nums.size(),a[++j],1);
			if(calc()>k) modify(1,1,nums.size(),a[j--],-1);
			ans=max(ans,j-i+1);
			modify(1,1,nums.size(),a[i],-1);
		}
		writeln(ans);
	}
	return 0;
}