#include <bits/stdc++.h>
using namespace std;
/*
#if __has_include(<boost/multiprecision/cpp_int.hpp>)
	#include <boost/multiprecision/cpp_int.hpp>
	#include <boost/multiprecision/cpp_dec_float.hpp>
	using bll = boost::multiprecision::cpp_int;
	using bdouble = boost::multiprecision::number<boost::multiprecision::cpp_dec_float<100>>;
	using namespace boost::multiprecision;
#endif
*/
#ifdef LOCAL_TEST
	#define BOOST_STACKTRACE_USE_ADDR2LINE
	#define BOOST_STACKTRACE_ADDR2LINE_LOCATION /usr/local/opt/binutils/bin/addr2line
	#define _GNU_SOURCE 1
	#include <boost/stacktrace.hpp>
	namespace std {
		template<typename T> class dvector : public std::vector<T> {
		public:
			dvector() : std::vector<T>() {}
			explicit dvector(size_t n, const T& value = T()) : std::vector<T>(n, value) {}
			dvector(const std::vector<T>& v) : std::vector<T>(v) {}
			dvector(const std::initializer_list<T> il) : std::vector<T>(il) {}
			dvector(const std::string::iterator first, const std::string::iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::iterator first, const typename std::vector<T>::iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::reverse_iterator first, const typename std::vector<T>::reverse_iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::const_iterator first, const typename std::vector<T>::const_iterator last) : std::vector<T>(first, last) {}
			dvector(const typename std::vector<T>::const_reverse_iterator first, const typename std::vector<T>::const_reverse_iterator last) : std::vector<T>(first, last) {}
			T& operator[](size_t n) {
				try { return this->at(n); } catch (const std::exception& e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; return this->at(n); }
			}
			const T& operator[](size_t n) const {
				try { return this->at(n); } catch (const std::exception& e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; return this->at(n); }
			}
		};
	}
	class dbool {
	private:
		bool boolvalue;
	public:
		dbool() : boolvalue(false) {}
		dbool(bool b) : boolvalue(b) {}
		operator bool&() { return boolvalue; }
		operator const bool&() const { return boolvalue; }
	};
	#define vector dvector
	#define bool dbool
	class SIGFPE_exception : std::exception {};
	class SIGSEGV_exception : std::exception {};
	void catch_SIGFPE([[maybe_unused]] int e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; throw SIGFPE_exception(); }
	void catch_SIGSEGV([[maybe_unused]] int e) { std::cerr << boost::stacktrace::stacktrace() << '\n'; throw SIGSEGV_exception(); }
	signed convertedmain();
	signed main() { signal(SIGFPE, catch_SIGFPE); signal(SIGSEGV, catch_SIGSEGV); return convertedmain(); }
	#define main() convertedmain()
#endif
#ifdef LOCAL_DEV
	template<typename T1, typename T2> std::ostream& operator<<(std::ostream& s, const std::pair<T1, T2>& p) {
		return s << "(" << p.first << ", " << p.second << ")"; }
	template <typename T, size_t N> std::ostream& operator<<(std::ostream& s, const std::array<T, N>& a) {
		s << "{ "; for (size_t i = 0; i < N; ++i){ s << a[i] << "\t"; } s << "}"; return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::set<T>& se) {
		s << "{ "; for (auto itr = se.begin(); itr != se.end(); ++itr){ s << (*itr) << "\t"; } s << "}"; return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::multiset<T>& se) {
		s << "{ "; for (auto itr = se.begin(); itr != se.end(); ++itr){ s << (*itr) << "\t"; } s << "}"; return s; }
	template<typename T1, typename T2> std::ostream& operator<<(std::ostream& s, const std::map<T1, T2>& m) {
		s << "{\n"; for (auto itr = m.begin(); itr != m.end(); ++itr){ s << "\t" << (*itr).first << " : " << (*itr).second << "\n"; } s << "}"; return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::deque<T>& v) {
		for (size_t i = 0; i < v.size(); ++i){ s << v[i]; if (i < v.size() - 1) s << "\t"; } return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::vector<T>& v) {
		for (size_t i = 0; i < v.size(); ++i){ s << v[i]; if (i < v.size() - 1) s << "\t"; } return s; }
	template<typename T> std::ostream& operator<<(std::ostream& s, const std::vector<std::vector<T>>& vv) {
		s << "\\\n"; for (size_t i = 0; i < vv.size(); ++i){ s << vv[i] << "\n"; } return s; }
	void debug_impl() { std::cerr << '\n'; }
	template<typename Head, typename... Tail> void debug_impl(Head head, Tail... tail) { std::cerr << " " << head << (sizeof...(tail) ? "," : ""); debug_impl(tail...); }
	#define debug(...) do { std::cerr << ":" << __LINE__ << " (" << #__VA_ARGS__ << ") ="; debug_impl(__VA_ARGS__); } while (false)
#else
	#define debug(...) do {} while (false)
#endif
//#define int long long
using ll = long long;
//constexpr int INF = (ll)1e9 + 7; //INT_MAX = (1<<31)-1 = 2147483647
constexpr ll INF = (ll)1e18; //(1LL<<63)-1 = 9223372036854775807
constexpr ll MOD = (ll)1e9 + 7; //primitive root = 5
//constexpr ll MOD = 998244353; //primitive root = 3
constexpr double EPS = 1e-9;
constexpr ll dx[4] = {1, 0, -1, 0};
constexpr ll dy[4] = {0, 1, 0, -1};
constexpr ll dx8[8] = {1, 0, -1, 0, 1, 1, -1, -1};
constexpr ll dy8[8] = {0, 1, 0, -1, 1, -1, 1, -1};
#define rep(i, n)   for(ll i=0, i##_length=(n); i< i##_length; ++i)
#define repeq(i, n) for(ll i=1, i##_length=(n); i<=i##_length; ++i)
#define rrep(i, n)   for(ll i=(n)-1; i>=0; --i)
#define rrepeq(i, n) for(ll i=(n)  ; i>=1; --i)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
void p() { std::cout << '\n'; }
template<typename Head, typename... Tail> void p(Head head, Tail... tail) { std::cout << head << (sizeof...(tail) ? " " : ""); p(tail...); }
template<typename T> inline void pv(std::vector<T>& v) { for(ll i=0, N=v.size(); i<N; i++) std::cout << v[i] << " \n"[i==N-1]; }
template<typename T> inline bool chmax(T& a, T b) { return a < b && (a = b, true); }
template<typename T> inline bool chmin(T& a, T b) { return a > b && (a = b, true); }
template<typename T> inline void uniq(std::vector<T>& v) { v.erase(std::unique(v.begin(), v.end()), v.end()); }

/*-----8<-----template-----8<-----*/

template< typename Monoid, typename OperatorMonoid, typename F >
class SegmentTreeArithmeticLazy {
public:
	ll sz;
	vector<Monoid> data;
	vector<pair<OperatorMonoid,OperatorMonoid>> lazy;
	const F f;
	const Monoid M1;
	const OperatorMonoid OM0;

	SegmentTreeArithmeticLazy(ll n, const F &f, const Monoid &M1, const OperatorMonoid &OM0)
	 : f(f), M1(M1), OM0(OM0) {
		sz = 1;
		while(sz < n) sz <<= 1;
		data.assign(sz*2, M1);
		lazy.assign(sz*2, {OM0,OM0});
	}

	//区間 [L,R) を 初項 p 公差 q の等差数列へ置換
	void update(ll L, ll R, Monoid p, Monoid q) {
		updateHelper(1, L, R, 0, sz, p-q*L, q);
	}

	Monoid query(ll L, ll R) {
		return queryHelper(1, L, R, 0, sz);
	}

private:
	void eval(ll k, ll L, ll R) {
		if (lazy[k].first != OM0 || lazy[k].second != OM0) {
			//data[k] = g(data[k], lazy[k]);
			data[k] = f(lazy[k].first, lazy[k].first + lazy[k].second*(R-L-1));
			if (R - L > 1) {
				//lazy[k*2] = h(lazy[k*2], lazy[k]/2);//???
				//lazy[k*2+1] = h(lazy[k*2+1], lazy[k]/2);//???
				lazy[k*2] = lazy[k];
				lazy[k*2+1] = {lazy[k].first + lazy[k].second*(R-L)/2, lazy[k].second};
			}
			lazy[k] = {OM0,OM0};
		}
	}

	void updateHelper(ll k, ll a, ll b, ll L, ll R, Monoid p, Monoid q) {
		eval(k, L, R);
		if (b <= L || R <= a) return;
		if (a <= L && R <= b) {
			//lazy[k] = h(lazy[k], val*(R-L));//???
			lazy[k] = {p, q};
			eval(k, L, R);
			return;
		}
		ll mid = L + (R - L) / 2;
		updateHelper(k*2, a, b, L, mid, p, q);//???
		updateHelper(k*2+1, a, b, mid, R, p+q*((R-L)/2), q);//???
		data[k] = f(data[k*2], data[k*2+1]);
	}
	
	Monoid queryHelper(ll k, ll a, ll b, ll L, ll R) {
		if (b <= L || R <= a) return M1;
		eval(k, L, R);
		if (a <= L && R <= b) return data[k];
		ll mid = L + (R - L) / 2;
		Monoid sum1 = queryHelper(k*2, a, b, L, mid);
		Monoid sum2 = queryHelper(k*2+1, a, b, mid, R);
		return f(sum1, sum2);
	}
};
template< typename Monoid, typename OperatorMonoid, typename F>
std::ostream& operator<<(std::ostream& s, SegmentTreeArithmeticLazy<Monoid,OperatorMonoid,F>& seg) { 
	for(ll i=0; i<seg.sz; i++) s << seg.query(i,i+1) << "\t\n"[i==seg.sz-1];
	return s;
}


//https://tsutaj.hatenablog.com/entry/2017/03/30/224339
template< typename Monoid, typename OperatorMonoid, typename F, typename G, typename H >
class SegmentTreeLazy {
public:
	ll sz;
	vector<Monoid> data;
	vector<OperatorMonoid> lazy;
	const F f;
	const G g;
	const H h;
	const Monoid M1;
	const OperatorMonoid OM0;

	SegmentTreeLazy(ll n, const F &f, const G &g, const H &h, const Monoid &M1, const OperatorMonoid &OM0)
	 : f(f), g(g), h(h), M1(M1), OM0(OM0) {
		sz = 1;
		while(sz < n) sz <<= 1;
		data.assign(sz*2, M1);
		lazy.assign(sz*2, OM0);
	}

	void update(ll L, ll R, OperatorMonoid val) {
		updateHelper(1, L, R, 0, sz, val);
	}

	Monoid query(ll L, ll R) {
		return queryHelper(1, L, R, 0, sz);
	}

	// 関数check を満たす/満たさない境目のindexを返す
	// 返却値 = 満たす要素数 = 満たさない最初のindex
	template<typename Func>
	ll partitionpoint(ll L, ll R, const Func &check){
		return partitionpointHelper(1, L, R, 0, sz, check);
	}

private:
	void eval(ll k, ll L, ll R) {
		if (lazy[k] != OM0) {
			data[k] = g(data[k], lazy[k]);
			if (R - L > 1) {
				lazy[k*2] = h(lazy[k*2], lazy[k]);//???
				lazy[k*2+1] = h(lazy[k*2+1], lazy[k]);//???
			}
			lazy[k] = OM0;
		}
	}

	void updateHelper(ll k, ll a, ll b, ll L, ll R, OperatorMonoid val) {
		if (b <= L || R <= a) return;
		eval(k, L, R);
		if (a <= L && R <= b) {
			lazy[k] = h(lazy[k], val);//???
			eval(k, L, R);
			return;
		}
		ll mid = L + (R - L) / 2;
		updateHelper(k*2, a, b, L, mid, val);//???
		updateHelper(k*2+1, a, b, mid, R, val);//???
		Monoid sum1 = g(data[k*2], lazy[k*2]);
		Monoid sum2 = g(data[k*2+1], lazy[k*2+1]);
		data[k] = f(sum1, sum2);
	}
	
	Monoid queryHelper(ll k, ll a, ll b, ll L, ll R) {
		if (b <= L || R <= a) return M1;
		eval(k, L, R);
		if (a <= L && R <= b) return data[k];
		ll mid = L + (R - L) / 2;
		Monoid sum1 = queryHelper(k*2, a, b, L, mid);
		Monoid sum2 = queryHelper(k*2+1, a, b, mid, R);
		return f(sum1, sum2);
	}

	template<typename Func>
	ll partitionpointHelper(ll k, ll a, ll b, ll L, ll R, const Func &check) {
		eval(k, L, R);
		// 条件を満たす or [a,b)が[l,r)の範囲外 -> 一番右端を返す
		if (check(data[k]) || R <= a || b <= L) return R;
		// 自分が葉ならその位置をreturn
		if (L+1 == R) return L;
		ll mid = L + (R - L) / 2;
		ll index = partitionpointHelper(k*2, a, b, L, mid, check);
		if (index != mid) return index;
		return partitionpointHelper(k*2+1, a, b, mid, R, check);
	}
};
template< typename Monoid, typename OperatorMonoid, typename F, typename G, typename H >
std::ostream& operator<<(std::ostream& s, SegmentTreeLazy<Monoid,OperatorMonoid,F,G,H>& seg) { 
	for(ll i=0; i<seg.sz; i++) s << seg.query(i,i+1) << "\t\n"[i==seg.sz-1];
	return s;
}

/*-----8<-----library-----8<-----*/

void solve() {
	ll H, W;
	cin >> H >> W;
	vector<ll> A(H), B(H);
	rep(i, H) { cin >> A[i] >> B[i]; A[i]--; }

	auto REPLACE = [](ll x,ll y){return y>=0 ? y : x;};
	SegmentTreeLazy<ll,ll,decltype(REPLACE),decltype(REPLACE),decltype(REPLACE)> seg(W, REPLACE, REPLACE, REPLACE, -1, -1);

	// 区間等差数列代入, 区間min/max
	// 第4引数の値はlazyの記号として使っているため、updateに指定しない値とすること
	auto MIN = [](ll x,ll y){return min(x,y);};
	SegmentTreeArithmeticLazy<ll,ll,decltype(MIN)> segA(W, MIN, INF, -INF);

	rep(i,W)seg.update(i,i+1,i);
	segA.update(0,W,0,0);

	vector<ll> ans(H, -1);
	rep(i,H){
		ll val = B[i]==W ? INF : B[i];
		// l:A[i]以上, r:B[i]以上の最初のindex
		ll l=seg.partitionpoint(0, W, [&](ll x){ return A[i]>x;});
		ll r=seg.partitionpoint(0, W, [&](ll x){ return B[i]>x;});
		debug(seg);
		debug(A[i],l,B[i],r);
		seg.update(l, r, val);

		// infpos:INF以上の最初のindex
		ll infpos=seg.partitionpoint(0, W, [&](ll x){ return INF>x;});
		segA.update(l, min(r,infpos),  val-l, -1);
		if(infpos<r)segA.update(infpos, r, INF, 0);

		ll t=segA.query(0, W);
		if(t>=INF)break;
		ans[i]=t+i+1;
	}
	
	rep(i,H) cout << ans[i] << '\n';
}

// https://atcoder.jp/contests/abc177/tasks/abc177_f
signed main() {
	std::cin.tie(nullptr);
	std::ios::sync_with_stdio(false);
	//ll Q; cin >> Q; while(Q--)solve();
	solve();
	return 0;
}


Measured memory_bytes: 28564