#line 2 "header.hpp"

//%snippet.set('header')%
//%snippet.fold()%
#ifndef HEADER_H
#define HEADER_H

// template version 2.0
using namespace std;
#include <bits/stdc++.h>

// varibable settings
const long long INF = 1e18;
template <class T> constexpr T inf = numeric_limits<T>::max() / 2.1;

#define _overload3(_1, _2, _3, name, ...) name
#define _rep(i, n) repi(i, 0, n)
#define repi(i, a, b) for (ll i = (ll)(a); i < (ll)(b); ++i)
#define rep(...) _overload3(__VA_ARGS__, repi, _rep, )(__VA_ARGS__)
#define _rrep(i, n) rrepi(i, 0, n)
#define rrepi(i, a, b) for (ll i = (ll)((b)-1); i >= (ll)(a); --i)
#define r_rep(...) _overload3(__VA_ARGS__, rrepi, _rrep, )(__VA_ARGS__)
#define each(i, a) for (auto &&i : a)
#define all(x) (x).begin(), (x).end()
#define sz(x) ((int)(x).size())
#define pb(a) push_back(a)
#define mp(a, b) make_pair(a, b)
#define mt(...) make_tuple(__VA_ARGS__)
#define ub upper_bound
#define lb lower_bound
#define lpos(A, x) (lower_bound(all(A), x) - A.begin())
#define upos(A, x) (upper_bound(all(A), x) - A.begin())
template <class T> inline void chmax(T &a, const T &b) { if ((a) < (b)) (a) = (b); }
template <class T> inline void chmin(T &a, const T &b) { if ((a) > (b)) (a) = (b); }
template <typename X, typename T> auto make_table(X x, T a) { return vector<T>(x, a); }
template <typename X, typename Y, typename Z, typename... Zs> auto make_table(X x, Y y, Z z, Zs... zs) { auto cont = make_table(y, z, zs...); return vector<decltype(cont)>(x, cont); }

#define cdiv(a, b) (((a) + (b)-1) / (b))
#define is_in(x, a, b) ((a) <= (x) && (x) < (b))
#define uni(x) sort(all(x)); x.erase(unique(all(x)), x.end())
#define slice(l, r) substr(l, r - l)

typedef long long ll;
typedef long double ld;
using vl = vector<ll>;
using vvl = vector<vl>;
using pll = pair<ll, ll>;

template <typename T>
using PQ = priority_queue<T, vector<T>, greater<T>>;
void check_input() { assert(cin.eof() == 0); int tmp; cin >> tmp; assert(cin.eof() == 1); }

#if defined(PCM) || defined(LOCAL)
#else
#define dump(...) ;
#define dump_1d(...) ;
#define dump_2d(...) ;
#define cerrendl ;
#endif

#endif /* HEADER_H */
//%snippet.end()%
#line 2 "solve.cpp"
template<class T=ll> using vec = vector<T>;
struct Fast { Fast() { std::cin.tie(0); ios::sync_with_stdio(false); } } fast;

template <typename T, typename E>
struct segment_tree_lazy {  //{{{
    // T: 値の型
    // E: update作用素
    using F = function<T(T, T)>;
    using G = function<T(T, E)>;
    using H = function<E(E, E)>;
    int n, height;
    F f;   // 区間のマージ
    G g;   // 更新をどのように行うか
    H h;   // 複数の更新のまとめ方
    T ti;  // 値の単位元
    E ei;  // 恒等置換
    vector<T> dat;
    vector<E> laz;
    segment_tree_lazy() {}
    segment_tree_lazy(F f, G g, H h, T ti, E ei)
        : f(f), g(g), h(h), ti(ti), ei(ei) {}

    void init(int n_) { /*{{{*/
        n = 1;
        height = 0;
        while (n < n_) n <<= 1, height++;
        dat.assign(2 * n, ti);
        laz.assign(2 * n, ei);
    } /*}}}*/

    void build(const vector<T> &v) { /*{{{*/
        int n_ = v.size();
        init(n_);
        for (int i = 0; i < n_; i++) dat[n + i] = v[i];
        for (int i = n - 1; i; i--)
            dat[i] = f(dat[(i << 1) | 0], dat[(i << 1) | 1]);
    } /*}}}*/

    inline T reflect(int k) { /*{{{*/
        return laz[k] == ei ? dat[k] : g(dat[k], laz[k]);
    } /*}}}*/

    inline void propagate(int k) { /*{{{*/
        if (laz[k] == ei) return;
        laz[(k << 1) | 0] = h(laz[(k << 1) | 0], laz[k]);
        laz[(k << 1) | 1] = h(laz[(k << 1) | 1], laz[k]);
        dat[k] = reflect(k);
        laz[k] = ei;
    } /*}}}*/

    inline void thrust(int k) { /*{{{*/
        for (int i = height; i; i--) propagate(k >> i);
    } /*}}}*/

    inline void recalc(int k) { /*{{{*/
        while (k >>= 1)
            dat[k] = f(reflect((k << 1) | 0), reflect((k << 1) | 1));
    } /*}}}*/

    void update(int a, int b, E x) { /*{{{*/
        if (a >= b) return;
        thrust(a += n);
        thrust(b += n - 1);
        for (int l = a, r = b + 1; l < r; l >>= 1, r >>= 1) {
            if (l & 1) laz[l] = h(laz[l], x), l++;
            if (r & 1) --r, laz[r] = h(laz[r], x);
        }
        recalc(a);
        recalc(b);
    } /*}}}*/

    void set_val(int a, T x) { /*{{{*/
        thrust(a += n);
        dat[a] = x;
        laz[a] = ei;
        recalc(a);
    } /*}}}*/

    T query(int a, int b) { /*{{{*/
        if (a >= b) return ti;
        thrust(a += n);
        thrust(b += n - 1);
        T vl = ti, vr = ti;
        for (int l = a, r = b + 1; l < r; l >>= 1, r >>= 1) {
            if (l & 1) vl = f(vl, reflect(l++));
            if (r & 1) vr = f(reflect(--r), vr);
        }
        return f(vl, vr);
    } /*}}}*/

    template <typename C>
        int find(int st, C &check, T &acc, int k, int l, int r) { /*{{{*/
            if (l + 1 == r) {
                acc = f(acc, reflect(k));
                return check(acc) ? k - n : -1;
            }
            propagate(k);
            int m = (l + r) >> 1;
            if (m <= st) return find(st, check, acc, (k << 1) | 1, m, r);
            if (st <= l && !check(f(acc, dat[k]))) {
                acc = f(acc, dat[k]);
                return -1;
            }
            int vl = find(st, check, acc, (k << 1) | 0, l, m);
            if (~vl) return vl;
            return find(st, check, acc, (k << 1) | 1, m, r);
        } /*}}}*/

    template <typename C>
        int find(int st, C &check) { /*{{{*/
            T acc = ti;
            return find(st, check, acc, 1, 0, n);
        } /*}}}*/
};    //}}}
// Sample:
// -----------------------------------------------
// init
// * このコードはRSQに対応していないのでRSQをする場合は別のものを使用するように注意

// how to use
// rep(i, n) lseg.set_val(i, a[i]);
// lseg.update(l, r, x); // [l, r)
// lseg.query(l, r); // [l, r)
// -----------------------------------------------

int solve() {
    ll h,w;cin>>h>>w;
    dump(h,w);

    vl a(h), b(h);
    rep(i, h){
        cin>>a[i]>>b[i];
        a[i]--;b[i]--;
    }

    set<pll> st;
    multiset<ll> ms;
    rep(j, w){
        st.insert(mp(j, j));  // (current, start)
        ms.insert(0);
    }
    st.insert(mp(w, -INF));
    dump(st);
    dump(ms);
    rep(k, 0, h){
        cerrendl;
        for (auto it = st.lb(mp(a[k], -1)); ;) {
            if (it->first > b[k]) break;
            else if ((*next(it)).first > b[k]) {
                auto nx = mp(b[k]+1, it->second);
                auto nv = b[k]+1 - it->second;
                ms.erase(ms.find(it->first - it->second));
                it = st.erase(it);
                if (b[k]+1 < w){
                    st.insert(nx);
                    ms.insert(nv);
                }
                break;
            }
            else{
                ms.erase(ms.find(it->first - it->second));
                it = st.erase(it);
            }
        }
        dump(st);
        dump(ms, sz(ms));
        cout << (sz(ms)==0 ? -1 : *ms.begin()+k+1) << endl;
    }

    return 0; 
}


int main(){/*{{{*/
    solve();
    check_input();
    return 0;
}/*}}}*/


Measured memory_bytes: 28256