#line 1 "main.cpp"
#line 2 "/Users/kaage/Desktop/ProgrammingWorkspace/library/other/template.hpp"
#define _CRT_SECURE_NO_WARNINGS
#pragma target("avx2")
#pragma optimize("O3")
#pragma optimize("unroll-loops")
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <memory>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <string.h>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#define rep(i,n) for(int i=0;i<(n);i++)
#define REP(i,n) for(int i=1;i<=(n);i++)
#define all(V) V.begin(),V.end()
typedef unsigned int uint;
typedef long long lint;
typedef unsigned long long ulint;
typedef std::pair<int, int> P;
typedef std::pair<lint, lint> LP;
constexpr int INF = INT_MAX/2;
constexpr lint LINF = LLONG_MAX/2;
constexpr double eps = DBL_EPSILON;
constexpr double PI=3.141592653589793238462643383279;
template<class T>
class prique :public std::priority_queue<T, std::vector<T>, std::greater<T>> {};
template <class T, class U>
inline bool chmax(T& lhs, const U& rhs) {
	if (lhs < rhs) {
		lhs = rhs;
		return 1;
	}
	return 0;
}
template <class T, class U>
inline bool chmin(T& lhs, const U& rhs) {
	if (lhs > rhs) {
		lhs = rhs;
		return 1;
	}
	return 0;
}
inline lint gcd(lint a, lint b) {
	while (b) {
		lint c = a;
		a = b; b = c % b;
	}
	return a;
}
inline lint lcm(lint a, lint b) {
	return a / gcd(a, b) * b;
}
bool isprime(lint n) {
	if (n == 1)return false;
	for (int i = 2; i * i <= n; i++) {
		if (n % i == 0)return false;
	}
	return true;
}
template<typename T>
T mypow(T a, lint b) {
	T res(1);
	while(b){
		if(b&1)res*=a;
		a*=a;
		b>>=1;
	}
	return res;
}
lint modpow(lint a, lint b, lint m) {
	lint res(1);
	while(b){
		if(b&1){
			res*=a;res%=m;
		}
		a*=a;a%=m;
		b>>=1;
	}
	return res;
}
template<typename T>
void printArray(std::vector<T>& vec) {
	rep(i, vec.size()){
		std::cout << vec[i];
		std::cout<<(i==(int)vec.size()-1?"\n":" ");
	}
}
template<typename T>
void printArray(T l, T r) {
	T rprev = std::prev(r);
	for (T i = l; i != rprev; i++) {
		std::cout << *i << " ";
	}
	std::cout << *rprev << std::endl;
}
LP extGcd(lint a,lint b) {
	if(b==0)return {1,0};
	LP s=extGcd(b,a%b);
	std::swap(s.first,s.second);
	s.second-=a/b*s.first;
	return s;
}
LP ChineseRem(const lint& b1,const lint& m1,const lint& b2,const lint& m2) {
	lint p=extGcd(m1,m2).first;
	lint tmp=(b2-b1)*p%m2;
	lint r=(b1+m1*tmp+m1*m2)%(m1*m2);
	return std::make_pair(r,m1*m2);
}
template<typename F>
inline constexpr decltype(auto) lambda_fix(F&& f){
	return [f=std::forward<F>(f)](auto&&... args){
		return f(f,std::forward<decltype(args)>(args)...);
	};
}
#line 2 "main.cpp"
class SegTree{
	int n=1;
	std::vector<P> node;
	std::vector<int> lazy;
	std::vector<bool> lazyflag;
	int val(P p){return p.second-p.first;}
	P comp(P lhs,P rhs){
		if(val(lhs)<val(rhs))return lhs;
		return rhs;
	}
	void eval(int k,int l,int r){
		if(lazyflag[k]){
			node[k].first=r-1;
			node[k].second=lazy[k];
			if(k<n){
				lazyflag[k<<1]=lazyflag[k<<1|1]=true;
				lazy[k<<1]=lazy[k<<1|1]=lazy[k];
			}
			lazyflag[k]=false;
		}
	}
public:
	SegTree(int m){
		while(n<m)n*=2;
		node.resize(2*n);lazy.resize(2*n);lazyflag.resize(2*n);
		for(int i=n;i<2*n;i++)node[i]={i-n,i-n};
		for(int i=n-1;i>0;i--)node[i]=comp(node[i<<1],node[i<<1|1]);
	}
	void update(int a,int b,int x,int k=1,int l=0,int r=-1){
		if(r==-1)r=n;
		eval(k,l,r);
		if(b<=l||r<=a)return;
		if(a<=l&&r<=b){
			lazy[k]=x;
			lazyflag[k]=true;
			eval(k,l,r);
			return;
		}
		update(a,b,x,k<<1,l,(l+r)>>1);
		update(a,b,x,k<<1|1,(l+r)>>1,r);
		node[k]=comp(node[k<<1],node[k<<1|1]);
	}
	int query(int a,int b,int k=1,int l=0,int r=-1){
		if(r==-1)r=n;
		eval(k,l,r);
		if(b<=l||r<=a)return INF;
		if(a<=l&&r<=b)return val(node[k]);
		int vl=query(a,b,k<<1,l,(l+r)>>1);
		int vr=query(a,b,k<<1|1,(l+r)>>1,r);
		return std::min(vl,vr);
	}
	P query2(int a,int k=1,int l=0,int r=-1){
		if(r==-1)r=n;
		eval(k,l,r);
		if(a+1<=l||r<=a)return {-1,-1};
		if(a<=l&&r<=a+1)return node[k];
		P vl=query2(a,k<<1,l,(l+r)>>1);
		P vr=query2(a,k<<1|1,(l+r)>>1,r);
		return vl.first!=-1?vl:vr;
	}
	void debug(){
		REP(i,2*n-1)std::cout<<node[i].second<<" ";
		std::cout<<std::endl;
	}
};
int H,W,a[200010],b[200010];
int main(){
	std::cin>>H>>W;
	rep(i,H){
		std::cin>>a[i]>>b[i];
		a[i]--;b[i]--;
	}
	SegTree st(W);
	rep(i,H){
		int lmin=-1,lmax=W;
		while(lmin+1<lmax){
			int mid=(lmin+lmax)/2;
			if(st.query2(mid).second<a[i])lmin=mid;
			else lmax=mid;
		}
		int rmin=-1,rmax=W;
		while(rmin+1<rmax){
			int mid=(rmin+rmax)/2;
			if(b[i]<st.query2(mid).second)rmax=mid;
			else rmin=mid;
		}
		//std::cout<<lmax<<" "<<rmin+1<<std::endl;
		if(b[i]!=W-1)st.update(lmax,rmin+1,b[i]+1);
		else st.update(lmax,rmin+1,INF);
		//st.debug();
		if(H+W<=st.query(0,W))std::cout<<-1<<std::endl;
		else std::cout<<st.query(0,W)+i+1<<std::endl;
	}
	return 0;
}

Measured memory_bytes: 10808