import math
from bisect import bisect_left, bisect_right
from typing import Generic, Iterable, Iterator, TypeVar, Union, List

T = TypeVar('T')


class SortedSet(Generic[T]):
    BUCKET_RATIO = 50
    REBUILD_RATIO = 170

    def _build(self, a=None) -> None:
        """Evenly divide `a` into buckets."""
        if a is None: a = list(self)
        size = self.size = len(a)
        bucket_size = int(math.ceil(math.sqrt(size / self.BUCKET_RATIO)))
        self.a = [a[size * i // bucket_size: size * (i + 1) // bucket_size] for i in range(bucket_size)]

    def __init__(self, a: Iterable[T] = []) -> None:
        """Make a new SortedSet from iterable. / O(N) if sorted and unique / O(N log N)"""
        a = list(a)
        if not all(a[i] < a[i + 1] for i in range(len(a) - 1)):
            a = sorted(set(a))
        self._build(a)

    def __iter__(self) -> Iterator[T]:
        for i in self.a:
            for j in i: yield j

    def __reversed__(self) -> Iterator[T]:
        for i in reversed(self.a):
            for j in reversed(i): yield j

    def __len__(self) -> int:
        return self.size

    def __str__(self) -> str:
        s = str(list(self))
        return "{" + s[1: len(s) - 1] + "}"

    def _find_bucket(self, x: T) -> List[T]:
        """Find the bucket which should contain x. self must not be empty."""
        for a in self.a:
            if x <= a[-1]: return a
        return a

    def __contains__(self, x: T) -> bool:
        if self.size == 0: return False
        a = self._find_bucket(x)
        i = bisect_left(a, x)
        return i != len(a) and a[i] == x

    def add(self, x: T) -> bool:
        """Add an element and return True if added. / O(√N)"""
        if self.size == 0:
            self.a = [[x]]
            self.size = 1
            return True
        a = self._find_bucket(x)
        i = bisect_left(a, x)
        if i != len(a) and a[i] == x: return False
        a.insert(i, x)
        self.size += 1
        if len(a) > len(self.a) * self.REBUILD_RATIO:
            self._build()
        return True

    def discard(self, x: T) -> bool:
        """Remove an element and return True if removed. / O(√N)"""
        if self.size == 0: return False
        a = self._find_bucket(x)
        i = bisect_left(a, x)
        if i == len(a) or a[i] != x: return False
        a.pop(i)
        self.size -= 1
        if len(a) == 0: self._build()
        return True

    def lt(self, x: T) -> Union[T, None]:
        """Find the largest element < x, or None if it doesn't exist."""
        for a in reversed(self.a):
            if a[0] < x:
                return a[bisect_left(a, x) - 1]

    def le(self, x: T) -> Union[T, None]:
        """Find the largest element <= x, or None if it doesn't exist."""
        for a in reversed(self.a):
            if a[0] <= x:
                return a[bisect_right(a, x) - 1]

    def gt(self, x: T) -> Union[T, None]:
        """Find the smallest element > x, or None if it doesn't exist."""
        for a in self.a:
            if a[-1] > x:
                return a[bisect_right(a, x)]

    def ge(self, x: T) -> Union[T, None]:
        """Find the smallest element >= x, or None if it doesn't exist."""
        for a in self.a:
            if a[-1] >= x:
                return a[bisect_left(a, x)]

    def __getitem__(self, x: int) -> T:
        """Return the x-th element, or IndexError if it doesn't exist."""
        if x < 0: x += self.size
        if x < 0: raise IndexError
        for a in self.a:
            if x < len(a): return a[x]
            x -= len(a)
        raise IndexError

    def index(self, x: T) -> int:
        """Count the number of elements < x."""
        ans = 0
        for a in self.a:
            if a[-1] >= x:
                return ans + bisect_left(a, x)
            ans += len(a)
        return ans

    def index_right(self, x: T) -> int:
        """Count the number of elements <= x."""
        ans = 0
        for a in self.a:
            if a[-1] > x:
                return ans + bisect_right(a, x)
            ans += len(a)
        return ans



class RangeSet:
    def __init__(self):
        self.ss = SortedSet()
        self.ss.add((INF*2, INF))

    def merge(self, l: int, r: int) -> tuple[int, int]:
        t = self.ss.ge((l, -1))
        assert t is not None

        sr, sl = t  # [sl, sr)
        if r < sl:
            self.ss.add((r, l))
            return l, r

        if sl <= l and r <= sr:
            return sl, sr

        self.ss.discard(t)
        start = min(l, sl)
        if r <= sr:
            self.ss.add((sr, start))
            return start, sr

        return self.merge(start, r)


INF = 1 << 60
D, Q = map(int, input().split())
rset = RangeSet()
ans = 0
for _ in range(Q):
    A, B = map(int, input().split())
    l, r = rset.merge(A, B+1)
    ans = max(ans, r-l)
    #print(f'{A=} {B=}')
    #print(f'   {l=} {r=}')
    print(ans)