//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using db = double;
using ld = long double;
template <typename T> using V = vector<T>;
template <typename T> using VV = vector<vector<T>>;
#define fs first
#define sc second
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define eb emplace_back
#define lb lower_bound
#define ub upper_bound
#define all(v) (v).begin(), (v).end()
#define siz(v) (ll)(v).size()
#define rep(i, a, n) for(ll i = a; i < (ll)(n); ++i)
#define repr(i, a, n) for(ll i = n - 1; (ll)a <= i; --i)
#define ENDL '\n'
typedef pair<int, int> Pi;
typedef pair<ll, ll> PL;
constexpr ll mod = 1000000007;  // 998244353;
constexpr ll INF = 1000000099;
constexpr ll LINF = (ll)(1e18 + 99);
const ld PI = acos((ld)-1);
const vector<ll> dx = {-1, 1, 0, 0}, dy = {0, 0, -1, 1};
template <typename T, typename U> inline bool chmin(T& t, const U& u) {
  if(t > u) {
    t = u;
    return 1;
  }
  return 0;
}
template <typename T, typename U> inline bool chmax(T& t, const U& u) {
  if(t < u) {
    t = u;
    return 1;
  }
  return 0;
}
template <typename T> inline T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }

template <typename T, typename Y> inline T mpow(T a, Y n) {
  T res = 1;
  for(; n; n >>= 1) {
    if(n & 1) res = res * a;
    a = a * a;
  }
  return res;
}

template <typename T, typename Y>
ostream& operator<<(ostream& os, const pair<T, Y>& p) {
  return os << "{" << p.fs << "," << p.sc << "}";
}
template <typename T> ostream& operator<<(ostream& os, const V<T>& v) {
  os << "{";
  for(auto e : v) os << e << ",";
  return os << "}";
}
template <typename... Args> void debug(Args&... args) {
  for(auto const& x : {args...}) { cerr << x << ' '; }
  cerr << ENDL;
}

ll n, m;
V<ll> a, b, ans;

ll dp[200020] = {};

signed main() {
  cin.tie(0);
  cerr.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(20);
  cin >> n >> m;
  a.resize(n);
  b.resize(n);
  ans.assign(n + 1, INF);

  rep(i, 0, n) {
    cin >> a[i];
    cin >> b[i];
  }

  set<ll> se;
  multiset<ll> val;
  rep(i, 1, m + 1) {
    se.insert(i);
    val.insert(dp[i]);
  }

  rep(i, a[0], b[0] + 1) {
    se.erase(i);
    val.erase(val.lb(dp[i]));
    dp[i] = INF;
  }
  if(se.size()) ans[0] = 1;

  rep(i, 1, n) {
    if(b[i] < m) {
      auto itr = se.ub(b[i] + 1);
      if(itr != se.begin()) {
        ll pre = *(--itr);

        if(dp[b[i]+1]<INF)val.erase(val.lb(dp[b[i]+1]));
        dp[b[i] + 1] = dp[pre] + b[i] + 1 - pre;

        val.insert(dp[b[i]+1]);
        se.insert(b[i] + 1);
      }
    }

    while(se.size() && se.lb(a[i]) != se.end() && (*se.lb(a[i])) <= b[i]) {
      auto itr = se.lb(a[i]);
      val.erase(val.lb(dp[*itr]));      
      dp[*itr] = INF;
      se.erase(itr);
    }

    if(se.empty()) break;
    ans[i]=*(val.begin()) + i+1;
  }

  rep(i, 0, n) {
    if(ans[i] >= INF)
      cout << -1 << ENDL;
    else
      cout << ans[i] << ENDL;
  }
}
//! ( . _ . ) !
// CHECK overflow,vector_size,what to output?

Measured memory_bytes: 28252