For problem statement at 1000-1999/1300-1399/1300-1309/1307/problemC.txt this is a correct solution, but verifier at 1000-1999/1300-1399/1300-1309/1307/verifierC.go ends with All tests passed can you fix the verifier? ```go
package main

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

func main() {
	reader := bufio.NewReader(os.Stdin)
	line, _ := reader.ReadString('\n')
	s := strings.TrimSpace(line)
	n := len(s)
	if n == 0 {
		fmt.Println(0)
		return
	}
	var freq [26]int
	for _, ch := range s {
		freq[ch-'a']++
	}
	var maxF int = 0
	for _, v := range freq {
		if v > maxF {
			maxF = v
		}
	}
	var seen [26]int64
	var pairC [26][26]int64
	for i := 0; i < n; i++ {
		c := int(s[i] - 'a')
		for x := 0; x < 26; x++ {
			pairC[x][c] += seen[x]
		}
		seen[c]++
	}
	var maxP int64 = 0
	for x := 0; x < 26; x++ {
		for y := 0; y < 26; y++ {
			if pairC[x][y] > maxP {
				maxP = pairC[x][y]
			}
		}
	}
	ans := maxP
	if int64(maxF) > ans {
		ans = int64(maxF)
	}
	fmt.Println(ans)
}
```