#include <iostream>
#include <vector>
#include <map>
#include <set>
using namespace std;
using ll = int64_t;

int main() {
  ll H,W;
  cin >> H >> W;
  ll INF = static_cast<ll>((H+1)*W);
  vector<ll> A(H, 0);
  vector<ll> B(H, 0);
  for(ll i=0; i<H; i++) {
    cin >> A[i] >> B[i];
  }
  map<ll,ll> M;
  multiset<ll> V;
  for(ll i=1; i<=W; i++) {
    M.insert(make_pair(i, 0));
    V.insert(0);
  }
  for(ll i=0; i<H; i++) {
    ll bp1 = INF;
    auto it = M.lower_bound(A[i]);
    while(true) {     
      if(it != M.end() && it->first<=B[i]) {
        bp1 = min(bp1, it->second + (B[i]+1-it->first));
        V.erase(V.find(it->second));
        M.erase(it++);
      } else {
        break;
      }
    }
    if(bp1 < INF && B[i]+1<=W) {
      if((M.count(B[i]+1)==0))
      	M[B[i]+1] = bp1,V.insert(bp1);
      else{
      	if(M[B[i]+1]>bp1)
          V.erase(V.find(M[B[i]+1])),M[B[i]+1]=bp1,V.insert(bp1);
      }
    }
    if(V.empty()) {		
      while(i<H)
		cout<<-1<<"\n",++i;
      return 0;
    } else {
      cout << ((*V.begin())+i+1) << endl;
    }
  }
}
