#include <bits/stdc++.h>
#define rep(i,j,k) for(int i=(j);i<=(k);i++)
#define per(i,j,k) for(int i=(j);i>=(k);i--)
#define uint unsigned int
#define ll long long
#define ull unsigned long long
#define db double
#define ldb long double
#define pii pair<int,int>
#define pll pair<ll,ll>
#define mkp make_pair
#define eb emplace_back
#define SZ(S) (int)S.size()
//#define mod 998244353
//#define mod 1000000007
#define inf 0x3f3f3f3f
#define linf 0x3f3f3f3f3f3f3f3f
using namespace std;

template <class T>
void chkmax(T &x,T y){
	if(x < y) x = y;
}

template <class T>
void chkmin(T &x,T y){
	if(x > y) x = y;
}

inline int popcnt(int x){
	return __builtin_popcount(x);
}

inline int ctz(int x){
	return __builtin_ctz(x);
}


/*ll power(ll p,int k = mod - 2){
	ll ans = 1;
	while(k){
		if(k % 2 == 1) ans = ans * p % mod;
		p = p * p % mod;
		k /= 2;	
	}
	return ans;
}*/
int T,n;
ll k;
int a[500005];

multiset <int> P,Q;//P 的 max <= Q 的 min,钦点 P 的 size 较大,如果不均衡的话
ll sum;//Q 和减 P 和
void ins(int val){
	if(P.empty()){
		sum -= val;
		P.insert(val);
		return;
	}
	auto it = prev(P.end());
	if(val <= *it){
		sum -= val;
		P.insert(val);
	}else{
		sum += val;
		Q.insert(val);
	}
}

void del(int val){
	auto it = P.find(val);
	if(it != P.end()){
		sum += val;
		P.erase(it);
		return;
	}
	it = Q.find(val);
	if(it != Q.end()){
		sum -= val;
		Q.erase(it);
		return;
	}
	assert(0);
}

void maintain(){
	while(SZ(Q) > SZ(P)){
		auto it = Q.begin();
		sum -= 2 * (*it);
		P.insert(*it);
		Q.erase(it);
	}
	while(SZ(P) >= SZ(Q) + 2){
		auto it = prev(P.end());
		sum += 2 * (*it);
		Q.insert(*it);
		P.erase(it);
	}
}

ll getcost(){
/*	printf("current state: sum=%lld\n",sum);
	for(int val:P) printf("%d ",val);
	printf("\n");
	for(int val:Q) printf("%d ",val);
	printf("\n");*/
	if(SZ(P) == SZ(Q)) return sum;
	auto it = prev(P.end());
	return sum + *it;
}

void solve(){
	scanf("%d%lld",&n,&k);
	rep(i,1,n){
		scanf("%d",&a[i]);
		a[i] -= i;
	}
	P.clear();Q.clear();
	sum = 0;
	int l = 1,ans = 0;
	rep(r,1,n){
		ins(a[r]);
		maintain();
		while(getcost() > k){
			del(a[l++]);
			maintain();
		}
		chkmax(ans,r - l + 1);
	}
	printf("%d\n",ans);
}

int main(){
//	freopen("test.in","r",stdin);
	scanf("%d",&T);
	while(T--) solve();
	return 0;
}