#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cfloat>
#include <chrono>
#include <climits>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <unordered_map>
#include <unordered_set>
#include <vector>
using namespace std;

template <class T1, class T2>
ostream& operator << (ostream& out, const pair <T1, T2> p)
{
    out << '(' << p.first << ',' << p.second << ')';
    return out;
}

template <class T1, class T2>
istream& operator >> (istream& in, pair<T1, T2> &p)
{
    in >> p.first >> p.second;
    return in;
}

template <class T>
istream& operator >> (istream& in, vector<T> &v)
{
    for (T &x : v)
        in >> x;
    return in;
}

template <class T>
ostream& operator << (ostream& out, const vector<vector<T>> &v)
{
    for (const vector<T> &x : v)
        out << x << '\n';
    return out;
}

template <class T>
ostream& operator << (ostream& out, const vector<T> &v)
{
    for (const T &x : v)
        out << x << ' ';
    return out;
}

long long gcd (long long a, long long b)
{
    if (b > a)
        swap(a, b);
    return (b ? gcd(b, a % b) : a);
}

using ll   = long long;
using pii  = pair<int, int>;
using pll  = pair<long long, long long>;
using tiii = pair<pair<int, int>, int>;
using vi   = vector<int>;
using vl   = vector<long long>;
using vvi  = vector<vector<int>>;
using vvl  = vector<vector<long long>>;

#define F          first
#define S          second
#define First      first.first
#define Second     first.second
#define Third      second
#define mp         make_pair
#define rep(i,a,b) for (int i = (a); i < (b); i++)
#define per(i,b,a) for (int i = (b); i > (a); i--)
#define all(x)     x.begin(), x.end()
#define ret(x)     return cout << x, 0;
#define throwex    throw runtime_error ("Found the error.");

// const int h = 1000000007;

template <class elem_T = long long, class upd_T = long long>
class SegTree
{
    private:
        const int underlying_array_size;
        const elem_T merge_identity = INT_MAX;
        const upd_T update_identity = 0;
        elem_T merge(const elem_T x, const elem_T y)
        {
            return min(x, y);
        }
        elem_T update_elem(const elem_T x, const upd_T y)
        {
            return x + y;
        }
        upd_T update_lazy(const upd_T x, const upd_T y)
        {
            return x + y;
        }
        vector<elem_T> seg_tree;
        vector<upd_T> lazy;
        void build(int node, int start, int end, vector<elem_T> &v)
        {
            if(start == end)
                seg_tree[node] = v[start];
            else
            {
                const int mid = (start + end) / 2;
                build(2 * node + 1, start, mid, v);
                build(2 * node + 2, mid + 1, end, v);
                seg_tree[node] = merge(seg_tree[2 * node + 1], seg_tree[2 * node + 2]);
            }
        }
        void update_range(int node, int start, int end, int l, int r, upd_T val)
        {
            if(l <= start and end <= r)
                lazy[node] = update_lazy(lazy[node], val);
            if(lazy[node] != update_identity)
            {
                if(start != end)
                {
                    lazy[2 * node + 1] = update_lazy(lazy[2 * node + 1], lazy[node]);
                    lazy[2 * node + 2] = update_lazy(lazy[2 * node + 2], lazy[node]);
                }
                seg_tree[node] = update_elem(seg_tree[node], lazy[node]);
                lazy[node] = update_identity;
            }
            if(end < l or start > r)
                return;
            if(l <= start and end <= r)
                return;
            const int mid = (start + end) / 2;
            update_range(2 * node + 1, start, mid, l, r, val);
            update_range(2 * node + 2, mid + 1, end, l, r, val);
            seg_tree[node] = merge(seg_tree[2 * node + 1], seg_tree[2 * node + 2]);
        }
        elem_T query(int node, int start, int end, int l, int r)
        {
            if(end < l or start > r)
                return merge_identity;
            if(lazy[node] != update_identity)
            {
                if(start != end)
                {
                    lazy[2 * node + 1] = update_lazy(lazy[2 * node + 1], lazy[node]);
                    lazy[2 * node + 2] = update_lazy(lazy[2 * node + 2], lazy[node]);
                }
                seg_tree[node] = update_elem(seg_tree[node], lazy[node]);
                lazy[node] = update_identity;
            }
            if(l <= start and end <= r)
                return seg_tree[node];
            const int mid = (start + end) / 2;
            return merge(
                query(2 * node + 1, start, mid, l, r),
                query(2 * node + 2, mid + 1, end, l, r));
        }

    public:
        SegTree(const int n) : underlying_array_size(n)
        {
            vector<elem_T> v(underlying_array_size, merge_identity);
            seg_tree.resize(4 * underlying_array_size, merge_identity);
            lazy.resize(4 * underlying_array_size, update_identity);
            build(0, 0, underlying_array_size - 1, v);
        }
        SegTree(vector<elem_T> &v) : underlying_array_size(v.size())
        {
            seg_tree.resize(4 * underlying_array_size, merge_identity);
            lazy.resize(4 * underlying_array_size, update_identity);
            build(0, 0, underlying_array_size - 1, v);
        }
        void update_range(int l, int r, upd_T val)
        {
            update_range(0, 0, underlying_array_size - 1, l, r, val);
        }
        elem_T query(int l, int r)
        {
            return query(0, 0, underlying_array_size - 1, l, r);
        }
};

signed main()
{
    ios::sync_with_stdio(false);
    #ifdef ONLINE_JUDGE
    cin.tie(nullptr);
    cerr.setstate(ios::failbit);
    #endif

    int h, w;
    cin >> h >> w;

    SegTree<> seg(w+1);
    seg.update_range(1, w, 1 - INT_MAX);
    set<int> s;
    rep(i,1,w+1)
        s.insert(i);
    rep(i,0,h)
    {
        int a, b;
        cin >> a >> b;
        s.insert(b + 1);
        while(1)
        {
            if(a > b)
                break;
            auto x = s.upper_bound(a);
            int en = (x == s.end() ? w : *x - 1);
            seg.update_range(a, en, seg.query(a - 1, a - 1) + 1 - seg.query(a, a));
            s.erase(a);
            a = en + 1;
        }
        cout << (seg.query(0, w) >= INT_MAX ? -1 : seg.query(0, w)) << '\n';
        seg.update_range(0, w, 1);
    }
}


Measured memory_bytes: 25080