// https://atcoder.jp/contests/abc177/tasks/abc177_f
//
#![allow(unused_imports)]
use std::io::*;
use std::io::Write;
use std::fmt::*;
use std::str::*;
use std::cmp::*;
use std::collections::*;

// Input macros.
// Original by tanakh: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
#[allow(unused_macros)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};

    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };

    ($iter:expr, mut $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, [ next / $t:tt ]) => {
        {
            let len = read_value!($iter, usize);
            (0..len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
        }
    };

    ($iter:expr, switch) => {
        {
            let ty = read_value!($iter, i32);
            if ty == 1 {
                vec![ty, read_value!($iter, i32), read_value!($iter, i32)]
            } else if ty == 2 {
                vec![ty, read_value!($iter, i32)]
            } else {
                vec![ty, read_value!($iter, i32)]
            }
        }
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

#[allow(unused_macros)]
macro_rules! read_line {
    ($t:tt) => {
        {
            let mut s = String::new();
            std::io::stdin().read_line(&mut s).unwrap();
            s.trim_right().parse::<$t>().unwrap()
        }
    }
}

#[allow(unused_macros)]
macro_rules! dvec {
    ($t:expr ; $len:expr) => {
        vec![$t; $len]
    };

    ($t:expr ; $len:expr, $($rest:expr),*) => {
        vec![dvec!($t; $($rest),*); $len]
    };
}

#[allow(unused_macros)]
macro_rules! ifv {
    ($t:expr, $a:expr, $b: expr) => {
        if $t { $a } else { $b }
    }
}

#[allow(unused_macros)]
macro_rules! fill {
    ($t:expr, $v:expr) => {
        for i in 0..$t.len() {
            $t[i] = $v;
        }
    };
}

#[allow(unused_macros)]
macro_rules! join {
    ($t:expr, $glue:expr) => {
        $t.into_iter().map(|w| w.to_string()).collect::<Vec<_>>().join($glue)
    };
}

#[allow(unused_macros)]
macro_rules! debug {
    ($($a:expr),*) => {
        println!(concat!($(stringify!($a), " = {:?}, "),*), $($a),*);
    }
}

// ===

const INF: usize = 1e12 as usize;

type PositionValue = (usize, usize);
type ValuePosition = (usize, usize);

struct PositionSet {
    position_value_set: BTreeSet<PositionValue>,
    value_position_set: BTreeSet<ValuePosition>
}

impl PositionSet {
    fn new() -> Self {
        Self {
            position_value_set: BTreeSet::new(),
            value_position_set: BTreeSet::new()
        }
    }

    fn push(&mut self, position: usize, value: usize) {
        self.position_value_set.insert((position, value));
        self.value_position_set.insert((value, position));
    }

    fn remove(&mut self, position: usize, value: usize) {
        self.position_value_set.remove(&(position, value));
        self.value_position_set.remove(&(value, position));
    }

    fn get_min_value(&self) -> usize {
        // debug!("getmin", self.value_position_set.min());
        self.value_position_set.iter().next().unwrap().0
    }
}

fn main() {
    input! {
        h: usize, w: usize,
        ng_ranges: [(usize, usize); h]
    };
    let mut pset = PositionSet::new();
    pset.push(0, INF);
    for i in 1..=w {
        pset.push(i, 0);
    }
    pset.push(w+1, INF);

    for i in 0..h {
        // debug!(pset.position_value_set);
        let (l, r) = ng_ranges[i];
        while let Some(&ptr) = pset.position_value_set.range((l,0)..(r,INF)).next() {
            pset.remove(ptr.0, ptr.1);
            let nptr = pset.position_value_set.range((ptr.0,0)..).next().unwrap();
            if r+1 < nptr.0 {
                let mv = r+1-ptr.0;
                pset.push(r+1, ptr.1+mv);
                break;
            }
        }

        let ans = pset.get_min_value()+i+1;
        println!("{}", ifv!(ans >= INF, -1, ans as i64));
    }
}


Measured memory_bytes: 22172