#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<cassert>
#include<complex>
#include<numeric>
#include<array>
using namespace std;

//#define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
constexpr ll mod = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int>P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
#define all(v) (v).begin(),(v).end()
typedef pair<ll, ll> LP;
typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-12;
const ld pi = acosl(-1.0);

ll mod_pow(ll x, ll n, ll m=mod) {
	ll res = 1;
	while (n) {
		if (n & 1)res = res * x % m;
		x = x * x % m; n >>= 1;
	}
	return res;
}
struct modint {
	ll n;
	modint() :n(0) { ; }
	modint(ll m) :n(m) {
		if (n >= mod)n %= mod;
		else if (n < 0)n = (n % mod + mod) % mod;
	}
	operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
modint operator+=(modint& a, modint b) { a.n += b.n; if (a.n >= mod)a.n -= mod; return a; }
modint operator-=(modint& a, modint b) { a.n -= b.n; if (a.n < 0)a.n += mod; return a; }
modint operator*=(modint& a, modint b) { a.n = ((ll)a.n * b.n) % mod; return a; }
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, ll n) {
	if (n == 0)return modint(1);
	modint res = (a * a) ^ (n / 2);
	if (n % 2)res = res * a;
	return res;
}

ll inv(ll a, ll p) {
	return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p);
}
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }

const int max_n = 1 << 19;
modint fact[max_n], factinv[max_n];
void init_f() {
	fact[0] = modint(1);
	for (int i = 0; i < max_n - 1; i++) {
		fact[i + 1] = fact[i] * modint(i + 1);
	}
	factinv[max_n - 1] = modint(1) / fact[max_n - 1];
	for (int i = max_n - 2; i >= 0; i--) {
		factinv[i] = factinv[i + 1] * modint(i + 1);
	}
}
modint comb(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[b] * factinv[a - b];
}

int gcd(int a, int b) {
	if (a < b)swap(a, b);
	while (b) {
		int r = a % b; a = b; b = r;
	}
	return a;
}

struct SegT {
private:
	int n; vector<ll> node, lazy;
	const ll init_c = INF;
public:
	SegT(int sz) {
		n = 1;
		while (n < sz)n <<= 1;
		node.resize(2 * n - 1, 0);
		lazy.resize(2 * n - 1, -mod-1);
	}
	ll f(ll a, ll b) {
		return min(a, b);
	}
	void eval(int k, int l, int r) {
		if (lazy[k] < -mod)return;
		node[k]= l - lazy[k];
		if (r - l > 1) {
			lazy[2 * k + 1] = lazy[k];
			lazy[2 * k + 2] = lazy[k];
		}
		lazy[k] = -mod-1;
	}
	void add(ll x, int a, int b, int k = 0, int l = 0, int r = -1) {
		if (r < 0)r = n;
		eval(k, l, r);
		if (r <= a || b <= l)return;
		if (a <= l && r <= b) {
			lazy[k] = x; eval(k, l, r);
		}
		else {
			add(x, a, b, k * 2 + 1, l, (l + r) / 2);
			add(x, a, b, k * 2 + 2, (l + r) / 2, r);
			node[k] = f(node[k * 2 + 1], node[k * 2 + 2]);
		}
	}
	ll query(int a, int b, int k = 0, int l = 0, int r = -1) {
		if (r < 0)r = n;
		eval(k, l, r);
		if (r <= a || b <= l)return init_c;
		if (a <= l && r <= b)return node[k];
		else {
			ll vl = query(a, b, k * 2 + 1, l, (l + r) / 2);
			ll vr = query(a, b, k * 2 + 2, (l + r) / 2, r);
			return f(vl, vr);
		}
	}

};

void solve() {
	int h, w; cin >> h >> w;
	vector<int> l(h), r(h);
	rep(i, h) {
		cin >> l[i] >> r[i];
		l[i]--; r[i]--;
	}
	SegT st(w);
	rep(i, h) {
		int val = -mod;
		if (l[i] > 0)val = l[i] - 1 - st.query(l[i] - 1, l[i]);
		//cout << "? " << val << "\n";
		st.add(val, l[i], r[i] + 1);
		ll ans = st.query(0, w);
		if (ans >= mod / 2)ans = -1;
		else ans += i + 1;
		cout << ans << "\n";

		/*cout << "start\n";
		rep(j, w) {
			cout << st.query(j, j + 1) << "\n";
		}*/

	}
}

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	//cout << fixed << setprecision(15);
	//init_f(); 
	//init();
	//expr();
	//int t; cin >> t; rep(i, t)
	solve();
	return 0;
}


Measured memory_bytes: 21132