//g++ t.cpp -o t && t < p.txt
//d>p.txt&&t<p.txt&&t2<p.txt

#include <iostream> // プログラムの耳と口
#include <vector> // 超有能配列秘書
#include <algorithm> // みんな大好きソートと二分探索
#include <queue> // きゅーちゃん、だいすき
#include <string> // to_string
#include <functional> // 関数を変数に入れる子
#include <set> // 値の取得・挿入・削除を高速に
#include <map> // setの妹 これまた優秀
#include <random> // 乱択さん
#include <ctime>
#include <bitset>

#define DB cerr<<"D"<<endl
using namespace std; using ll=long long; using ld=long double; const int INF=1e9; const ll LINF=1e18; const double dINF = 1e18; const ld ldINF = 1e18; const double EPS = 1e-6;
template<typename T, typename U, typename O> void caut(T a, U b, O c){cout<<"("<<a<<","<<b<<","<<c<<") ";} template<typename T, typename U> void caut(T a, U b){cout<<"("<<a<<","<<b<<") ";} template<typename T> void caut(T a){cout<<"("<<a<<") ";};
using P=pair<ll,ll>;
const ll M = 1e9+7;
ll mod_pow(ll x, ll a) { ll an = 1; while(a > 0) { if (a&1) an = an * x % M; x = x * x % M; a >>= 1;} return an;}
void add(ll& x, ll y) {x+=y; x%=M;}; void mul(ll& x, ll y) {x*=y; x%=M;}; template<typename T, typename U> void chmax(T& x, U y) {if (x<y) x=y;}; template<typename T, typename U> void chmin(T& x, U y) {if (x>y) x=y;}
bool vaild(int x, int y, int hh, int ww){return 0<=x&&x<hh&&0<=y&&y<ww;}
int keta(ll a) {int res=0; while(a>0) res+=a%10, a/=10; return res;}
const int up[]={1,-1,0,0}, lf[]={0,0,1,-1};
ll gcd(ll a, ll b) {if (b==0) return a; else return gcd(b, a%b);}

// CC0ライセンスのセグ木をのせます

template<class Monoid, class Action> struct SegTree {
    using FuncMonoid = function< Monoid(Monoid, Monoid) >;
    using FuncAction = function< void(Monoid&, Action) >;
    using FuncLazy = function< void(Action&, Action) >;
    FuncMonoid FM;
    FuncAction FA;
    FuncLazy FL;
    Monoid UNITY_MONOID;
    Action UNITY_LAZY;
    int SIZE, HEIGHT;
    vector<Monoid> dat;
    vector<Action> lazy;
    
    SegTree() { }
    SegTree(int n, const FuncMonoid fm, const FuncAction fa, const FuncLazy fl,
            const Monoid &unity_monoid, const Action &unity_lazy)
    : FM(fm), FA(fa), FL(fl), UNITY_MONOID(unity_monoid), UNITY_LAZY(unity_lazy) {
        SIZE = 1; HEIGHT = 0;
        while (SIZE < n) SIZE <<= 1, ++HEIGHT;
        dat.assign(SIZE * 2, UNITY_MONOID);
        lazy.assign(SIZE * 2, UNITY_LAZY);
    }
    void init(int n, const FuncMonoid fm, const FuncAction fa, const FuncLazy fl,
              const Monoid &unity_monoid, const Action &unity_lazy) {
        FM = fm; FA = fa; FL = fl;
        UNITY_MONOID = unity_monoid; UNITY_LAZY = unity_lazy;
        SIZE = 1; HEIGHT = 0;
        while (SIZE < n) SIZE <<= 1, ++HEIGHT;
        dat.assign(SIZE * 2, UNITY_MONOID);
        lazy.assign(SIZE * 2, UNITY_LAZY);
    }
    
    /* set, a is 0-indexed */
    void set(int a, const Monoid &v) { dat[a + SIZE] = v; }
    void build() {
        for (int k = SIZE - 1; k > 0; --k)
            dat[k] = FM(dat[k*2], dat[k*2+1]);
    }
    
    /* update [a, b) */
    inline void evaluate(int k) {
        if (lazy[k] == UNITY_LAZY) return;
        if (k < SIZE) FL(lazy[k*2], lazy[k]), FL(lazy[k*2+1], lazy[k]);
        FA(dat[k], lazy[k]);
        lazy[k] = UNITY_LAZY;
    }
    inline void update(int a, int b, const Action &v, int k, int l, int r) {
        evaluate(k);
        if (a <= l && r <= b)  FL(lazy[k], v), evaluate(k);
        else if (a < r && l < b) {
            update(a, b, v, k*2, l, (l+r)>>1), update(a, b, v, k*2+1, (l+r)>>1, r);
            dat[k] = FM(dat[k*2], dat[k*2+1]);
        }
    }
    inline void update(int a, int b, const Action &v) { update(a, b, v, 1, 0, SIZE); }
    
    /* get [a, b) */
    inline Monoid get(int a, int b, int k, int l, int r) {
        evaluate(k);
        if (a <= l && r <= b)
            return dat[k];
        else if (a < r && l < b)
            return FM(get(a, b, k*2, l, (l+r)>>1), get(a, b, k*2+1, (l+r)>>1, r));
        else
            return UNITY_MONOID;
    }
    inline Monoid get(int a, int b) { return get(a, b, 1, 0, SIZE); }
    inline Monoid operator [] (int a) { return get(a, a+1); }
    
    /* debug */
    void print() {
        for (int i = 0; i < SIZE; ++i) { cout << (*this)[i]; if (i != SIZE) cout << ","; }
        cout << endl;
    }
};

int main() {
  int h,w; cin>>h>>w;
  int a[h], b[h];
  for(int i=0;i<h;i++) {
    cin>>a[i]>>b[i]; a[i]--; b[i]--;
  }
  auto xx = [](int a, int b) { return min(a, b); };
  auto yy = [](int &a, int d) { a = d; };
  auto zz = [](int &d, int e) { d = e; };
  SegTree<int ,int> seg(w, xx, yy, zz, INF, -INF);
  auto x2 = [](int a, int b) { return max(a, b); };
  SegTree<int ,int> se2(w, x2, yy, zz, -INF, INF);
  for(int i=0;i<w;i++) seg.set(i,0);
  seg.build(); //seg.print();
  for(int i=0;i<w;i++) se2.set(i,i); // id
  se2.build();

  for(int i=0;i<h;i++) {
    //cout << "@"<<a[i]<<" "<<b[i]+1<<endl;
    if (b[i]+1 < w) {
      int t0 = se2.get(a[i], b[i]+1);
      //cout <<"*"<< t0<<endl;
      if (t0 != -1) {
        int t1 = se2.get(b[i]+1, b[i]+2);
        if (t0 > t1){
          se2.update(b[i]+1, b[i]+2, t0);
          //cout<<"*"<<b[i]+1<<" "<<t0<<endl;
          seg.update(b[i]+1, b[i]+2, b[i]+1-t0);
          //seg.print(); se2.print();
        }
      }
    }
    se2.update(a[i], b[i]+1, -1);
    seg.update(a[i], b[i]+1, INF);
    int gt = seg.get(0, w);
    if (gt == INF) cout<<-1<<endl;
    else cout<<gt+i+1<<endl;
    //seg.print(); se2.print();
  }
}
// ・配列の大きさok？　・priority_queueはgreater？　・debug消した？
// ・落ち着いて。提出まで4分待ってね……WJ……1/10……2/10……

// Thank you for making problems and running the contest


Measured memory_bytes: 12956