#include<bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 1e9 + 7;
//const int mod = 998244353;

const int64 infll = (1LL << 62) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;


template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 > &p) {
  os << p.first << " " << p.second;
  return os;
}

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

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

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

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename F >
struct FixPoint : F {
  FixPoint(F &&f) : F(forward< F >(f)) {}

  template< typename... Args >
  decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, forward< Args >(args)...);
  }
};

template< typename F >
inline decltype(auto) MFP(F &&f) {
  return FixPoint< F >{forward< F >(f)};
}


int main() {
  int H, W;
  cin >> H >> W;

  vector< int > A(H + 1), B(H + 1);
  A[0] = 0, B[0] = W;
  for(int i = 1; i <= H; i++) {
    cin >> A[i] >> B[i];
    --A[i];
  }
  // あの　ちがう　問題を　解いていました　あたま　ねねちゃんですか？
  map< int, int > mp;
  using pi = pair< int, int >;
  priority_queue< pi, vector< pi >, greater<> > que;
  for(int i = 0; i < W; i++) {
    mp[i] = 0;
    que.emplace(0, i);
  }

  for(int i = 1; i <= H; i++) {

    {
      auto it = mp.lower_bound(A[i]);
      pair< int, int > last(-1, -1);
      while(it != end(mp) && it->first < B[i]) {
        last = *it;
        it = mp.erase(it);
      }
      if(last.first != -1 && B[i] < W) {
        if(!mp.count(B[i])) mp[B[i]] = (B[i] - last.first) + last.second;
        else mp[B[i]] = min(mp[B[i]], (B[i] - last.first) + last.second);
        que.emplace(mp[B[i]], B[i]);
      }
    }

    if(B[i] < W) {
      auto it = mp.lower_bound(A[i]);
      if(it != begin(mp)) {
        --it;
        if(!mp.count(B[i])) mp[B[i]] = (B[i] - it->first) + it->second;
        else mp[B[i]] = min(mp[B[i]], (B[i] - it->first) + it->second);
        que.emplace(mp[B[i]], B[i]);
      }
    }
    while(!que.empty() && (!mp.count(que.top().second) || mp[que.top().second] != que.top().first)) que.pop();
    if(que.empty()) cout << -1 << "\n";
    else cout << que.top().first + i << "\n";
  }
}

Measured memory_bytes: 18152