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

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  
  int h, w;
  cin >> h >> w;
  
  map<int, int> mp; // mp[now] = start
  multiset<int> ms; // multiset of (now - start)
  for (int i = 0; i < w; i++) {
    mp[i] = i;
    ms.insert(0);
  }
  mp[2e8] = 1e8; // sentinel
  ms.insert(1e8); // sentinel
  
  for (int i = 0; i < h; i++) {
    int a, b;
    cin >> a >> b;
    a--;
    auto it1 = mp.lower_bound(a);
    auto it2 = mp.lower_bound(b);
    if (it1 != it2) {
      int start, now;
      auto it = it1;
      while (it != it2) {
        start = it->second;
        now = it->first;
        int start2 = it->second, now2 = it->first;
        ms.erase(ms.find(now2 - start2));
        it = mp.erase(it);
      }
      if (b < w) {
        now = b;
        if (mp.find(now) == mp.end()) {
          mp[now] = start;
          ms.insert(now - start);
        }
      }
    }
    if (*(ms.begin()) == 1e8) cout << -1 << '\n';
    else cout << *(ms.begin()) + i + 1 << '\n';
  }
}