For problem statement at 1000-1999/1100-1199/1180-1189/1186/problemF.txt this is a correct solution, but verifier at 1000-1999/1100-1199/1180-1189/1186/verifierF.go ends with All 100 tests passed can you fix the verifier? package main

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

type FastScanner struct {
	r *bufio.Reader
}

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

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')
		c2, err := fs.r.ReadByte()
		if err != nil {
			break
		}
		c = c2
	}
	return val * sign
}

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

	n := in.NextInt()
	m := in.NextInt()

	u := make([]int, m)
	v := make([]int, m)
	deg := make([]int, n+1)

	for i := 0; i < m; i++ {
		a := in.NextInt()
		b := in.NextInt()
		u[i] = a
		v[i] = b
		deg[a]++
		deg[b]++
	}

	cap := make([]int, n+1)
	for i := 1; i <= n; i++ {
		cap[i] = deg[i] / 2
	}

	T := n + (m+1)/2
	k := m
	deleted := make([]bool, m)

	for i := 0; i < m && k > T; i++ {
		a := u[i]
		b := v[i]
		if cap[a] > 0 && cap[b] > 0 {
			deleted[i] = true
			cap[a]--
			cap[b]--
			k--
		}
	}

	fmt.Fprintln(out, k)
	for i := 0; i < m; i++ {
		if !deleted[i] {
			fmt.Fprintln(out, u[i], v[i])
		}
	}
}