For problem statement at 0-999/800-899/860-869/864/problemD.txt this is a correct solution, but verifier at 0-999/800-899/860-869/864/verifierD.go ends with case 1 failed: runtime error: exit status 2
panic: runtime error: index out of range [27] with length 15

goroutine 1 [running]:
main.main()
	/tmp/build-557715780/solution.go:32 +0x5a4

input:14
27 6 15 24 17 19 7 9 10 9 5 6 16 2
exit status 1 can you fix the verifier? ```go
package main

import (
	"bufio"
	"container/heap"
	"fmt"
	"os"
)

type IntHeap []int

func (h IntHeap) Len() int            { return len(h) }
func (h IntHeap) Less(i, j int) bool  { return h[i] < h[j] }
func (h IntHeap) Swap(i, j int)       { h[i], h[j] = h[j], h[i] }
func (h *IntHeap) Push(x interface{}) { *h = append(*h, x.(int)) }
func (h *IntHeap) Pop() interface{} {
	old := *h
	n := len(old)
	x := old[n-1]
	*h = old[:n-1]
	return x
}

func main() {
	in := bufio.NewReader(os.Stdin)
	var n int
	fmt.Fscan(in, &n)
	a := make([]int, n)
	cnt := make([]int, n+1)
	for i := 0; i < n; i++ {
		fmt.Fscan(in, &a[i])
		cnt[a[i]]++
	}

	missing := &IntHeap{}
	heap.Init(missing)
	for v := 1; v <= n; v++ {
		if cnt[v] == 0 {
			heap.Push(missing, v)
		}
	}

	changed := 0
	for i := 0; i < n; i++ {
		x := a[i]
		if cnt[x] == 1 {
			continue
		}
		if missing.Len() == 0 {
			continue
		}
		m := (*missing)[0]
		if m < x {
			heap.Pop(missing)
			cnt[x]--
			a[i] = m
			changed++
		} else if cnt[x] > 1 {
			heap.Pop(missing)
			cnt[x]--
			a[i] = m
			changed++
		}
	}

	out := bufio.NewWriter(os.Stdout)
	fmt.Fprintln(out, changed)
	for i := 0; i < n; i++ {
		if i > 0 {
			fmt.Fprint(out, " ")
		}
		fmt.Fprint(out, a[i])
	}
	fmt.Fprintln(out)
	out.Flush()
}
```