#include <bits/stdc++.h>
#include <unistd.h>
#include <sys/time.h>
#include <stdlib.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<P, ll> T;
typedef pair<long double , ll> Ps;
typedef pair<ll, bool> Pb;

const ll INF = 1e18;
const ll fact_table = 3200008;
long double Pi = 3.1415926535897932384626;

priority_queue <ll> pql;
priority_queue <P> pqp;
priority_queue <P> bag;
//big priority queue
priority_queue <ll, vector<ll>, greater<ll> > pqls;
priority_queue <P, vector<P>, greater<P> > pqps;
//small priority queue
//top pop

ll dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
ll dy[8] = {0, 1, 0, -1, 1, -1, -1, 1};
//↓,→,↑,←


#define endl "\n"
#ifdef ENJAPMA
#undef endl
#endif

#define p(x) cout<<x<<endl;
#define el cout<<endl;
#define pe(x) cout<<x<<" ";
#define ps(x) cout<<fixed<<setprecision(25)<<x<<endl;
#define pu(x) cout<<(x);
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define CLEAR(a) a = decltype(a)();
#define pc(x) cout << x << ",";
#define rep(i, n) for (ll i = 0; i < (n); i ++)

// const ll mod = 998244353ll;
const ll mod = 1000000007ll;

ll mypow(ll a, ll b, ll mod) {ll x = 1; while (b) {while (!(b & 1)) {(a *= a) %= mod; b >>= 1;}(x *= a) %= mod; b--;} return x;}
void YES(bool cond) { if (cond) { p("YES");} else { p("NO");} return;}
void Yes(bool cond) { if (cond) { p("Yes");} else { p("No");} return;}
void line() { p("--------------------"); return;}

/*
ll fact[fact_table + 5], rfact[fact_table + 5];

void c3_init() {
    fact[0] = rfact[0] = 1;
    for (ll i = 1; i <= fact_table; i++) {
        fact[i] = (fact[i - 1] * i) % mod;
    }
    rfact[fact_table] = mypow(fact[fact_table], mod - 2, mod);
    for (ll i = fact_table; i >= 1; i--) {
        rfact[i - 1] = rfact[i] * i;
        rfact[i - 1] %= mod;
    }
    return;
}
ll c3(ll n, ll r) {
    return (((fact[n] * rfact[r]) % mod ) * rfact[n - r]) % mod;
}
*/
struct Timer {
    int64_t start;
    const int64_t CYCLES_PER_SEC = 2800000000;
    Timer() { reset(); }
    void reset() { start = getCycle(); }
    inline double get() { return (double)(getCycle() - start) / CYCLES_PER_SEC; }
    inline int64_t getCycle() {
        uint32_t low, high;
        __asm__ volatile ("rdtsc" : "=a" (low), "=d" (high));
        return ((int64_t)low) | ((int64_t)high << 32);
    }
};


bool multicase = false;

ll n, m, k, w, a, b, c, d, e, h, q, ans, sum, l;

typedef vector<ll> vec;
typedef vector<vector<ll>> mat;

struct LazySegmentTree1 {
private:
    int n;
    vector<ll> node, lazy;
    vector<bool> lazyFlag;
 
public:
    LazySegmentTree1(vector<ll> 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] = max(node[k], lazy[k] - r + 1);
            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, ll x, int k=0, int l=0, int r=-1) {
        //update node[a, b) to x
        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]);
        }
    }
 
    ll find(int a, int b, int k=0, int l=0, int r=-1) {
        //find minimum of node[a, b)
        if(r < 0) r = n;
        lazyEvaluate(k, l, r);
        if(b <= l || r <= a) return INF;
        if(a <= l && r <= b) return node[k];
        ll vl = find(a, b, 2*k+1, l, (l+r)/2);
        ll vr = find(a, b, 2*k+2, (l+r)/2, r);
        return min(vl, vr);
    }
};

struct LazySegmentTree2 {
private:
    int n;
    vector<ll> node, lazy;
    vector<bool> lazyFlag;
 
public:
    LazySegmentTree2(vector<ll> 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, ll x, int k=0, int l=0, int r=-1) {
        //update node[a, b) to x
        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]);
        }
    }
 
    ll find(int a, int b, int k=0, int l=0, int r=-1) {
        //find minimum of node[a, b)
        if(r < 0) r = n;
        lazyEvaluate(k, l, r);
        if(b <= l || r <= a) return INF;
        if(a <= l && r <= b) return node[k];
        ll vl = find(a, b, 2*k+1, l, (l+r)/2);
        ll vr = find(a, b, 2*k+2, (l+r)/2, r);
        return min(vl, vr);
    }
};

LazySegmentTree1 leftmost(vec(200001, 0));
LazySegmentTree2 leftmosttrue(vec(200001, 0));


ll leftfind(ll val){
    ll ok = w + 1, ng = 0;
    while(ok - ng > 1){
        ll mid = (ok + ng) / 2;
        if (leftmosttrue.find(mid, mid + 1) >= val) {
            ok = mid;
        } else {
            ng = mid;
        }
    }
    return ok;
}


void solve() {
    cin >> h >> w;
    vec x(h), y(h);
    for(int i=0;i<h;i++){
        cin >> x[i] >> y[i];
    }
    for(int i=1;i<=w;i++){
        leftmosttrue.update(i, i + 1, i);
    }
    for(int i=0;i<h;i++){
        ll l = leftfind(x[i]);
        ll r = leftfind(y[i]+1);
        leftmost.update(l, r, y[i] + 1);
        if (y[i] + 1 > w) {
            leftmost.update(l, r, INF);
        }
        leftmosttrue.update(l, r, y[i] + 1);
        ll ans = leftmost.find(1, w + 1);
        if (ans >= INF / 2) {
            p(-1);
            continue;
        }
        p(ans + i + 1);
    }

    return;
}

int main() {
    // init();
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    ll q, testcase = 1;
    if (multicase) {
        cin >> q;
    } else {
        q = 1;
    }
    while (q--) {
        // pu("Case ");pu("#");pu(testcase);pu(": ");
        solve();
        testcase++;
    }
    // solve();
    return 0;
}



Measured memory_bytes: 24528