package main

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

func configure(scanner *bufio.Scanner) {
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 1000005), 1000005)
}
func getNextString(scanner *bufio.Scanner) string {
	scanned := scanner.Scan()
	if !scanned {
		panic("scan failed")
	}
	return scanner.Text()
}
func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}
func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}
func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}
func main() {
	fp := os.Stdin
	wfp := os.Stdout
	extra := 0
	if os.Getenv("I") == "IronMan" {
		fp, _ = os.Open(os.Getenv("END_GAME"))
		extra = 100
	}
	scanner := bufio.NewScanner(fp)
	configure(scanner)
	writer := bufio.NewWriter(wfp)
	defer func() {
		r := recover()
		if r != nil {
			fmt.Fprintln(writer, r)
		}
		writer.Flush()
	}()
	solve(scanner, writer)
	for i := 0; i < extra; i++ {
		fmt.Fprintln(writer, "-----------------------------------")
		solve(scanner, writer)
	}
}
func solve(scanner *bufio.Scanner, writer *bufio.Writer) {
	h := getNextInt(scanner)
	w := getNextInt(scanner)
	rbt := newTreeWithIntComparator()
	rbt2 := newTreeWithIntComparator()
	for i := 0; i < w; i++ {
		rbt.Put(i, i)
		rbt2.Put(0, 1)
	}

	for i := 0; i < h; i++ {
		a := getNextInt(scanner) - 1
		b := getNextInt(scanner)
		x := -1
		for node, ok := rbt.Ceiling(a); ok && node.Key.(int) <= b; node, ok = rbt.Ceiling(a) {
			k := node.Key.(int)
			v := node.Value.(int)
			rbt.Remove(k)
			if x < v {
				x = v
			}
			rbt2.Remove(k - v)
		}
		if b < w && x != -1 {
			old, found := rbt.Get(b)
			if found && old.(int) > x {
				x = old.(int)
			}
			rbt.Put(b, x)
			rbt2.Put(b-x, 1)
		}
		if rbt2.Empty() {
			fmt.Fprintln(writer, -1)
			continue
		}
		fmt.Fprintln(writer, rbt2.Left().Key.(int)+i+1)
	}
}

type tree struct {
	Root       *node
	Comparator func(a, b interface{}) int
}
type node struct {
	Left, Right, Parent *node
	Key                 interface{}
	Value               interface{}
	size                int
}

func newTreeWithIntComparator() *tree {
	return newTree(func(a, b interface{}) int {
		aa := a.(int)
		bb := b.(int)
		if aa == bb {
			return 0
		}
		if aa < bb {
			return -1
		}
		return 1
	})
}
func newTree(comparator func(interface{}, interface{}) int) *tree {
	return &tree{Root: nil, Comparator: comparator}
}
func newNode(parent *node, key, value interface{}) *node {
	return &node{Parent: parent, Key: key, Value: value, size: 1}
}
func (n *node) IsRoot() bool {
	return n.Parent == nil
}
func (n *node) IsLeft() bool {
	return !n.IsRoot() && n.Parent.Left == n
}
func (n *node) IsRight() bool {
	return !n.IsRoot() && n.Parent.Right == n
}
func (n *node) Update() {
	n.size = 1 + n.Left.Size() + n.Right.Size()
}
func (n *node) Size() int {
	if n == nil {
		return 0
	}
	return n.size
}
func (n *node) Merge(m *node) *node {
	if n == nil {
		return m
	}
	if m == nil {
		return n
	}
	if n.Size() > m.Size() {
		n.AppendRight(n.Right.Merge(m))
		n.Update()
		return n
	}
	m.AppendLeft(n.Merge(m.Left))
	m.Update()
	return m
}
func (n *node) MaximumNode() *node {
	if n == nil {
		return n
	}
	if n.Right == nil {
		return n
	}
	return n.Right.MaximumNode()
}
func (n *node) MinimumNode() *node {
	if n == nil {
		return n
	}
	if n.Left == nil {
		return n
	}
	return n.Left.MinimumNode()
}
func (n *node) AppendLeft(m *node) {
	if n == nil {
		return
	}
	n.Left = m
	n.Update()
	if m == nil {
		return
	}
	m.Parent = n
}
func (n *node) AppendRight(m *node) {
	if n == nil {
		return
	}
	n.Right = m
	n.Update()
	if m == nil {
		return
	}
	m.Parent = n
}
func (t *tree) Put(key, value interface{}) {
	if t.Root == nil {
		t.Root = newNode(nil, key, value)
		return
	}
	now := t.Root
	for {
		compared := t.Comparator(key, now.Key)
		switch {
		// case compared == 0:
		// 	now.Value = value
		// 	return
		case compared <= 0:
			if now.Left == nil {
				now.Left = newNode(now, key, value)
				t.Update(now)
				return
			}
			now = now.Left
		case compared > 0:
			if now.Right == nil {
				now.Right = newNode(now, key, value)
				t.Update(now)
				return
			}
			now = now.Right
		}
	}
}
func (t *tree) Get(key interface{}) (interface{}, bool) {
	now := t.Lookup(key)
	if now == nil {
		return nil, false
	}
	return now.Value, true
}
func (t *tree) Lookup(key interface{}) *node {
	now := t.Root
	for now != nil {
		compared := t.Comparator(key, now.Key)
		switch {
		case compared == 0:
			return now
		case compared < 0:
			now = now.Left
		case compared > 0:
			now = now.Right
		}
	}
	return nil
}
func (t *tree) Remove(key interface{}) {
	now := t.Lookup(key)
	if now == nil {
		return
	}
	parent := now.Parent
	partialTree := now.Left.Merge(now.Right)
	switch {
	case now.IsRoot():
		t.Root = partialTree
		if t.Root != nil {
			t.Root.Parent = nil
		}
	case now.IsLeft():
		parent.AppendLeft(partialTree)
	case now.IsRight():
		parent.AppendRight(partialTree)
	}
	for parent != nil {
		parent.Update()
		parent = parent.Parent
	}
}
func (t *tree) Update(now *node) {
	for now != nil {
		now.Update()
		parent := now.Parent
		switch {
		case now.Left.Size() > now.Right.Size():
			t.RotateRight(now.Left)
		case now.Left.Size() < now.Right.Size():
			t.RotateLeft(now.Right)
		}
		now = parent
	}
}
func (t *tree) RotateLeft(now *node) {
	parent := now.Parent
	grand := parent.Parent
	parent.AppendRight(now.Left)
	now.AppendLeft(parent)
	switch {
	case grand == nil:
		t.Root = now
		now.Parent = nil
	case grand.Left == parent:
		grand.AppendLeft(now)
	case grand.Right == parent:
		grand.AppendRight(now)
	}
}
func (t *tree) RotateRight(now *node) {
	parent := now.Parent
	grand := parent.Parent
	parent.AppendLeft(now.Right)
	now.AppendRight(parent)
	switch {
	case grand == nil:
		t.Root = now
		t.Root.Update()
		now.Parent = nil
	case grand.Left == parent:
		grand.AppendLeft(now)
	case grand.Right == parent:
		grand.AppendRight(now)
	}
}
func (t *tree) Right() *node {
	return t.Root.MaximumNode()
}
func (t *tree) Left() *node {
	return t.Root.MinimumNode()
}
func (t *tree) Floor(key interface{}) (*node, bool) {
	now := t.Root
	var n *node
	for now != nil {
		compared := t.Comparator(key, now.Key)
		switch {
		case compared == 0:
			return now, true
		case compared < 0:
			now = now.Left
		case compared > 0:
			n = now
			now = now.Right
		}
	}
	return n, n != nil
}
func (t *tree) Ceiling(key interface{}) (*node, bool) {
	now := t.Root
	var n *node
	for now != nil {
		compared := t.Comparator(key, now.Key)
		switch {
		case compared == 0:
			return now, true
		case compared < 0:
			n = now
			now = now.Left
		case compared > 0:
			now = now.Right
		}
	}
	return n, n != nil
}
func (t *tree) Empty() bool {
	return t.Root == nil
}


Measured memory_bytes: 51784