package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
)

type FastScanner struct {
	r *bufio.Reader
}

func NewFastScanner() *FastScanner {
	return &FastScanner{r: bufio.NewReaderSize(os.Stdin, 1<<20)}
}

func (fs *FastScanner) NextInt64() int64 {
	sign := int64(1)
	val := int64(0)
	ch, _ := fs.r.ReadByte()
	for (ch < '0' || ch > '9') && ch != '-' {
		ch, _ = fs.r.ReadByte()
	}
	if ch == '-' {
		sign = -1
		ch, _ = fs.r.ReadByte()
	}
	for ch >= '0' && ch <= '9' {
		val = val*10 + int64(ch-'0')
		ch, _ = fs.r.ReadByte()
	}
	return val * sign
}

func main() {
	in := NewFastScanner()
	out := bufio.NewWriterSize(os.Stdout, 1<<20)
	defer out.Flush()

	t := int(in.NextInt64())
	for ; t > 0; t-- {
		n := int(in.NextInt64())
		c := in.NextInt64()
		b := make([]int64, n)
		for i := 0; i < n; i++ {
			a := in.NextInt64()
			b[i] = a + int64(i+1)
		}
		sort.Slice(b, func(i, j int) bool { return b[i] < b[j] })
		var sum int64
		ans := 0
		for i := 0; i < n; i++ {
			if sum+b[i] <= c {
				sum += b[i]
				ans++
			} else {
				break
			}
		}
		fmt.Fprintln(out, ans)
	}
}