For problem statement at 1000-1999/1900-1999/1910-1919/1917/problemC.txt this is a correct solution, but verifier at 1000-1999/1900-1999/1910-1919/1917/verifierC.go ends with case 4 failed
input:
1
3 2 18
3 1 3
1 1
expected: 0
 got: 9

exit status 1 can you fix the verifier? ```go
package main

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

type FastScanner struct {
	r *bufio.Reader
}

func NewFastScanner() *FastScanner {
	return &FastScanner{r: bufio.NewReader(os.Stdin)}
}

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

type BIT struct {
	n int
	t []int
}

func NewBIT(n int) *BIT {
	return &BIT{n: n, t: make([]int, n+2)}
}

func (b *BIT) Add(i, delta int) {
	for i <= b.n {
		b.t[i] += delta
		i += i & -i
	}
}

func (b *BIT) Sum(i int) int {
	s := 0
	for i > 0 {
		s += b.t[i]
		i -= i & -i
	}
	return s
}

func (b *BIT) FindByOrder(k int) int {
	idx := 0
	bit := 1
	for (bit << 1) <= b.n {
		bit <<= 1
	}
	for bit > 0 {
		next := idx + bit
		if next <= b.n && b.t[next] < k {
			k -= b.t[next]
			idx = next
		}
		bit >>= 1
	}
	return idx + 1
}

func main() {
	fs := NewFastScanner()
	out := bufio.NewWriter(os.Stdout)
	defer out.Flush()

	t := fs.NextInt()
	for ; t > 0; t-- {
		n, k, d := fs.NextInt(), fs.NextInt(), fs.NextInt()
		a := make([]int, n)
		for i := 0; i < n; i++ {
			a[i] = fs.NextInt()
		}
		v := make([]int, k)
		for i := 0; i < k; i++ {
			v[i] = fs.NextInt()
		}

		// buckets of indices by value of v[i]
		indicesByVal := make([][]int, n+1)
		for i := 0; i < k; i++ {
			w := v[i]
			if w > n {
				w = n
			}
			indicesByVal[w] = append(indicesByVal[w], i)
		}

		bit := NewBIT(k)
		alive := 0
		base0 := 0

		counts := make(map[int]int) // T -> multiplicity, for first segment events

		// process thresholds s from n down to 1
		for s := n; s >= 1; s-- {
			// add indices with v == s
			for _, idx := range indicesByVal[s] {
				bit.Add(idx+1, 1)
				alive++
			}
			rNeed := s - a[s-1]
			if rNeed == 0 {
				base0++
			} else if rNeed > 0 && alive > 0 {
				cnt := alive
				q := (rNeed - 1) / cnt
				rem := (rNeed - 1) % cnt
				idx1 := bit.FindByOrder(rem + 1) // 1..k
				posWithinCycle := idx1
				T := q*k + posWithinCycle
				if T <= d-1 {
					counts[T]++
				}
			}
		}

		ans := 0
		// candidate t = 0
		if d-1 >= 0 {
			remDays := d - (0 + 1)
			total := base0 + remDays/2
			if total > ans {
				ans = total
			}
		}
		// other candidates from counts
		for T, mult := range counts {
			if T > d-1 {
				continue
			}
			remDays := d - (T + 1)
			if remDays < 0 {
				continue
			}
			total := mult + remDays/2
			if total > ans {
				ans = total
			}
		}

		fmt.Fprintln(out, ans)
	}
}
```