#include <iostream>
#include <iomanip>
#include <sstream>
#include <vector>
#include <string>
#include <set>
#include <unordered_set>
#include <map>
#include <unordered_map>
#include <stack>
#include <queue>
#include <deque>
#include <algorithm>
#include <functional>
#include <iterator>
#include <limits>
#include <numeric>
#include <utility>
#include <type_traits>
#include <cmath>
#include <cassert>
#include <cstdio>

using namespace std;
using namespace placeholders;

using LL = long long;
using ULL = unsigned long long;
using VI = vector< int >;
using VVI = vector< vector< int > >;
using VS = vector< string >;
using ISS = istringstream;
using OSS = ostringstream;
using PII = pair< int, int >;
using VPII = vector< pair< int, int > >;
template < typename T = int > using VT = vector< T >;
template < typename T = int > using VVT = vector< vector< T > >;
template < typename T = int > using LIM = numeric_limits< T >;
template < typename T = int > using OSI = ostream_iterator< T >;

template < typename T > inline istream& operator>>( istream &s, vector< T > &v ){ for ( T &t : v ) { s >> t; } return s; }
template < typename T > inline ostream& operator<<( ostream &s, const vector< T > &v ){ for ( int i = 0; i < int( v.size() ); ++i ){ s << ( " " + !i ) << v[i]; } return s; }

void in_impl(){};
template < typename T, typename... TS > void in_impl( T &head, TS &... tail ){ cin >> head; in_impl( tail ... ); }
#define IN( T, ... ) T __VA_ARGS__; in_impl( __VA_ARGS__ );

template < typename T > inline T fromString( const string &s ) { T res; istringstream iss( s ); iss >> res; return res; }
template < typename T > inline string toString( const T &a ) { ostringstream oss; oss << a; return oss.str(); }

#define NUMBERED( name, number ) NUMBERED2( name, number )
#define NUMBERED2( name, number ) name ## _ ## number
#define REP1( n ) REP2( NUMBERED( REP_COUNTER, __LINE__ ), n )
#define REP2( i, n ) REP3( i, 0, n )
#define REP3( i, m, n ) for ( int i = ( int )( m ); i < ( int )( n ); ++i )
#define GET_REP( a, b, c, F, ... ) F
#define REP( ... ) GET_REP( __VA_ARGS__, REP3, REP2, REP1 )( __VA_ARGS__ )
#define FOR( e, c ) for ( auto &&e : c )
#define ALL( c ) begin( c ), end( c )
#define AALL( a ) ( remove_all_extents< decltype( a ) >::type * )a, ( remove_all_extents< decltype( a ) >::type * )a + sizeof( a ) / sizeof( remove_all_extents< decltype( a ) >::type )

#define SZ( v ) ( (int)( v ).size() )
#define EXISTS( c, e ) ( ( c ).find( e ) != ( c ).end() )

template < typename T > inline bool chmin( T &a, const T &b ){ if ( b < a ) { a = b; return true; } return false; }
template < typename T > inline bool chmax( T &a, const T &b ){ if ( a < b ) { a = b; return true; } return false; }

#define PB push_back
#define EM emplace
#define EB emplace_back
#define BI back_inserter

#define MP make_pair
#define fst first
#define snd second

#define DUMP( x ) cerr << #x << " = " << ( x ) << endl

//     Λ   Λ＿_
//  ／(*ﾟーﾟ)／＼
// ／| ￣U U￣|＼／
//   |      |／

constexpr int MOD = 998244353;

// セグメント木のユーティリティ
inline int chl( const int k )
{
	return k * 2 + 1;
}

inline int chr( const int k )
{
	return k * 2 + 2;
}

inline int mid( const int l, const int r )
{
	return ( l + r ) / 2;
}

#define LEFT( k, l, r ) chl( k ), l, mid( l, r )
#define RIGHT( k, l, r ) chr( k ), mid( l, r ), r

// segment tree, range add, sum
class SegmentTreeRAS
{
private:
	const int N;
	vector<int> data_overall, data_partial;

public:
	SegmentTreeRAS( const int n ) : N( n ), data_overall( 4 * N ), data_partial( 4 * N )
	{
		return;
	}

// 	SegmentTreeRAS( const vector<int> &src ) : N( src.size() ), data_overall( N * 4, 0 ), data_partial( N * 4, 0 )
// 	{
// 		REP( i, 0, N )
// 		{
// 			add( i, i + 1, src[i] );
// 		}
//
// 		return;
// 	}

	void add( const int a, const int b, const int x )
	{
		return add( a, b, x, 0, 0, N );
	}

	int sum( const int a, const int b )
	{
		return sum( a, b, 0, 0, N );
	}

private:
	void add( const int a, const int b, const int x, const int k, const int l, const int r )
	{
		if ( b <= l || r <= a )
		{
			return;
		}
		else if ( a <= l && r <= b )
		{
			( data_overall[k] += x ) %= MOD;
		}
		else
		{
			( data_partial[k] += (LL)( min( r, b ) - max( l, a ) ) * x ) %= MOD;;
			add( a, b, x, chl( k ), l, mid( l, r ) );
			add( a, b, x, chr( k ), mid( l, r ), r );
		}
	}

	int sum( const int a, const int b, const int k, const int l, const int r )
	{
		if ( b <= l || r <= a )
		{
			return 0;
		}
		else if ( a <= l && r <= b )
		{
			return ( data_partial[k] + (LL)( r - l ) * data_overall[k] ) % MOD;
		}
		else
		{
			int res = (LL)( min( r, b ) - max( l, a ) ) * data_overall[k];
			( res += sum( a, b, chl( k ), l, mid( l, r ) ) ) %= MOD;
			( res += sum( a, b, chr( k ), mid( l, r ), r ) ) %= MOD;;
			return res;
		}
	}
};
// SegmentTreeRAS( VI src )
// add( [ a, b ), x )
// sum( [ a, b ) )


int main()
{
	cin.tie( nullptr );
	ios::sync_with_stdio( false );
	cout << setprecision( 12 ) << fixed;

	IN( int, N, K );
	VI L( K ), R( K );
	REP( i, K )
	{
		cin >> L[i] >> R[i];
	}

	SegmentTreeRAS segtree( 2 * N + 2 );
	segtree.add( 0, 1, 1 );

	REP( i, N - 1 )
	{
		REP( j, K )
		{
			const int l = i + L[j];
			const int r = i + R[j];
			segtree.add( l, r + 1, segtree.sum( i, i + 1 ) );
		}
	}

	cout << segtree.sum( N - 1, N ) << endl;

	return 0;
}

Measured memory_bytes: 15624