#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define ull unsigned long long	
#define pb push_back
#define pii pair<ll,ll>
#define il inline

#define LEFT POS*2
#define RIGHT POS*2+1
#define fastio ios::sync_with_stdio(false), cin.tie(0)
const int N = 1e4+5;
ll n,m,A[N],B[N],lsh[N],tlt;
unordered_map<ll,ll> cvt;
bool vis[5*N];
struct Node{
	ll sum,l,r,lazy=0;
};
struct SGT{
	Node tr[4*N];
	ll base[N];
	il void _pushup(ll POS){
		tr[POS].sum = tr[LEFT].sum + tr[RIGHT].sum;
		return ;
	}
	il void _pushdown(ll POS){
		if(!tr[POS].lazy) return ;
		tr[LEFT].sum = (tr[LEFT].r-tr[LEFT].l+1) * tr[POS].lazy;
		tr[RIGHT].sum = (tr[RIGHT].r-tr[RIGHT].l+1) * tr[POS].lazy;
		tr[LEFT].lazy = tr[POS].lazy;
		tr[RIGHT].lazy = tr[POS].lazy;
		tr[POS].lazy = 0;
		return ;
	}
	il void build(ll POS,ll l,ll r){
		tr[POS].l=l,tr[POS].r=r, tr[POS].sum=tr[POS].lazy=0;
		if(l==r) return ;
		ll mid = l+r>>1;
		build(LEFT,l,mid),build(RIGHT,mid+1,r);
		return ;
	}
	il void modify(ll POS,ll cl,ll cr,ll v){
		ll l=tr[POS].l,r=tr[POS].r;
		if(cl>r || cr<l) return ;
		if(l>=cl && r<=cr){
			tr[POS].sum = (r-l+1) * v;
			tr[POS].lazy = v;
			return ;
		}
		_pushdown(POS);
		modify(LEFT,cl,cr,v),modify(RIGHT,cl,cr,v);
		_pushup(POS);
		return ;
	}
	il ll query(ll POS,ll cl,ll cr){
		ll l=tr[POS].l,r=tr[POS].r;
		if(cl>r || cr<l) { return 0; }
		if(l>=cl && r<=cr) { return tr[POS].sum; }
		_pushdown(POS);
		return query(LEFT,cl,cr) + query(RIGHT,cl,cr);
	}
} sgt;
signed main(){
	fastio;
	cin >> n >> m;
	lsh[++tlt] = n;  // 有极度坑人的数据，ai,bi>n
	for(int i=1; i<=m; i++){
		cin >> A[i] >> B[i];
		lsh[++tlt] = A[i], lsh[++tlt] = B[i], lsh[++tlt] = B[i]+1;// lsh[++tlt] = B[i]+1;
	}
	sort(lsh+1,lsh+tlt+1);
	tlt = unique(lsh+1,lsh+tlt+1) - lsh - 1;
	for(int i=1; i<=tlt; i++) cvt[lsh[i]] = i;
	sgt.build(1,1,tlt);
	for(int i=1; i<=m; i++) sgt.modify(1,cvt[A[i]],cvt[B[i]],i);
 	for(int i=1; i<=tlt; i++) vis[sgt.query(1,i,i)] = 1;
	ll ans = 0;
 	for(int i=1; i<=tlt; i++) if(vis[i]) ans++;
 	printf("%lld\n", ans);
	return 0;
}