#include <iostream>
#include <algorithm>
#include <utility>
#include <string>
#include <vector>
#include <set>
#include <stack>
#include <queue>
#include <map>
#include <math.h>
#include <string.h>
#include <iomanip>
#include <numeric>
#include <cstdlib>
#include <cstdint>
#include <cmath>
#include <functional>
#include <limits>
#include <cassert>
#include <bitset>
 
using namespace std;
 
/* template */
 
using ll = long long;
 
void debug_out() { std::cout << std::endl; }
 
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cout << H << " ";
  debug_out(T...);
}
 
#ifdef LOCAL
#define debug(...) cout << "debug: "; debug_out(__VA_ARGS__)
#else
#define debug(...) 
#endif
 
#define rep(i, a, n) for (int i = (int)(a); i < (int)(n); i++)
#define rrep(i, a, n) for (int i = ((int)(n-1)); i >= (int)(a); i--)
#define Rep(i, a, n) for (long long i = (long long)(a); i< (long long)(n); i++)
#define RRep(i, a, n) for (long long i = ((long long)(n-1ll)); i>=(long long)(a); i--)
#define all(v) (v).begin(),(v).end()
#define rall(v) (v).rbegin(),(v).rend()
 
template <typename T>
std::ostream& operator<<(std::ostream& os, std::vector<T> vec) {
  for (std::size_t i = 0; i < vec.size(); i++)os << vec[i] << (i + 1 == vec.size() ? "" : " ");
  return os;
}
 
struct Edge{
    int to;
    ll weight;
    Edge(int t, ll w) : to(t), weight(w){ }
};
 
struct edge{
    int from;
    int to;
    ll weight;
    edge(int f,int t,ll w) : from(f), to(t), weight(w){ }
};
 
 
using Graph = vector<vector<Edge>>;
using graph = vector<vector<int>>;
using edges = vector<edge>;
 
template <class T>
inline bool chmin(T &a, T b){
    if (a > b){
        a = b;
        return true;
    }
    return false;
}
 
template <class T>
inline bool chmax(T &a, T b){
    if (a < b){
        a = b;
        return true;
    }
    return false;
}
 
template <class T>
T lcm(T a, T b){
    return (a*b)/gcd(a,b);
}
 
ll ctoi(char c) {
	switch (c) {
	case '0': return 0; case '1': return 1; case '2': return 2;
	case '3': return 3; case '4': return 4; case '5': return 5;
	case '6': return 6; case '7': return 7; case '8': return 8;
	case '9': return 9;  default: return 0;
	}
}
 
constexpr ll LNF = 1LL<<50;
 
constexpr int INF = 1e9+7;
 
const long double PI=3.14159265358979323846;
 
 
vector<int> dx = {1,0,-1,0};
vector<int> dy = {0,1,0,-1};
 
/* template */

struct LazySegmentTree {
private:
    int n;
    vector<int> node, lazy;
    vector<bool> lazyFlag;

public:
    LazySegmentTree(vector<int> v) {
        int sz = (int)v.size();
        n = 1; while(n < sz) n *= 2;
        node.resize(2*n-1);
        lazy.resize(2*n-1, INF);
        lazyFlag.resize(2*n-1, false);

        for(int i=0; i<sz; i++) node[i+n-1] = v[i];
        for(int i=n-2; i>=0; i--) node[i] = min(node[i*2+1], node[i*2+2]);
    }

    void lazyEvaluate(int k, int l, int r) {
        if(lazyFlag[k]) {
            node[k] = lazy[k];
            if(r - l > 1) {
                lazy[k*2+1] = lazy[k*2+2] = lazy[k];
                lazyFlag[k*2+1] = lazyFlag[k*2+2] = true;
            }
            lazyFlag[k] = false;
        }
    }

    void update(int a, int b, int x, int k=0, int l=0, int r=-1) {
        if(r < 0) r = n;
        lazyEvaluate(k, l, r);
        if(b <= l || r <= a) return;
        if(a <= l && r <= b) {
            lazy[k] = x;
            lazyFlag[k] = true;
            lazyEvaluate(k, l, r);
        }
        else {
            update(a, b, x, 2*k+1, l, (l+r)/2);
            update(a, b, x, 2*k+2, (l+r)/2, r);
            node[k] = min(node[2*k+1], node[2*k+2]);
        }
    }

    int find(int a, int b, int k=0, int l=0, int r=-1) {
        if(r < 0) r = n;
        lazyEvaluate(k, l, r);
        if(b <= l || r <= a) return INF;
        if(a <= l && r <= b) return node[k];
        int vl = find(a, b, 2*k+1, l, (l+r)/2);
        int vr = find(a, b, 2*k+2, (l+r)/2, r);
        return min(vl, vr);
    }
};

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int h,w; cin >> h >> w;
    vector<int> s(w);
    rep(i,0,w){
        s[i] = i;
    }
    LazySegmentTree seg(s),ans(vector<int>(w,0));
    rep(i,0,h){
        int a,b; cin >> a >> b;
        a--;
        if(b<w){
            int y = seg.find(b-1,b);
            if(b-y>0){
                ans.update(b,b+1,min(b-seg.find(b-1,b),ans.find(b,b+1)));
            }
        }
        ans.update(a,b,INF);
        if(a>0){
            int x = seg.find(a-1,a);
            seg.update(a,b,x);
        }
        else{
            seg.update(a,b,INF);
        }
        ll c = ans.find(0,w)+i+1;
        if(c>10000000){
            c = -1;
        }
        cout << c << endl;
    }
}


Measured memory_bytes: 13044