#include using namespace std; #define rep(i, n) for(long long i=0;i<(long long)(n);i++) #define REP(i,k,n) for(long long i=k;i<(long long)(n);i++) #define all(a) a.begin(),a.end() #define pb emplace_back #define eb emplace_back #define lb(v,k) (lower_bound(all(v),k)-v.begin()) #define ub(v,k) (upper_bound(all(v),k)-v.begin()) #define fi first #define se second #define pi M_PI #define PQ(T) priority_queue #define SPQ(T) priority_queue,greater> #define dame(a) {out(a);return 0;} #define decimal cout< P; typedef tuple PP; typedef tuple PPP; typedef multiset S; using vi=vector; using vvi=vector; using vvvi=vector; using vvvvi=vector; using vp=vector

; using vvp=vector; using vb=vector; using vvb=vector; const ll inf=1001001001001001001; const ll INF=1001001001; const ll mod=998244353; const double eps=1e-10; template bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;} template bool chmax(T&a,T b){if(a void out(T a){cout< void outp(T a){cout<<'('< void outvp(T v){rep(i,v.size())cout<<'('< void outvvp(T v){rep(i,v.size())outvp(v[i]);} template void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout< void outvv(T v){rep(i,v.size())outv(v[i]);} template bool isin(T x,T l,T r){return (l)<=(x)&&(x)<=(r);} template void yesno(T b){if(b)out("yes");else out("no");} template void YesNo(T b){if(b)out("Yes");else out("No");} template void YESNO(T b){if(b)out("YES");else out("NO");} template void noyes(T b){if(b)out("no");else out("yes");} template void NoYes(T b){if(b)out("No");else out("Yes");} template void NOYES(T b){if(b)out("NO");else out("YES");} void outs(ll a,ll b){if(a>=inf-100)out(b);else out(a);} ll gcd(ll a,ll b){if(b==0)return a;return gcd(b,a%b);} ll modpow(ll a,ll b){ll res=1;a%=mod;while(b){if(b&1)res=res*a%mod;a=a*a%mod;b>>=1;}return res;} ll MX=1000005; vi primenumbers,f; void initprime(){ //O(loglogMX) f=vi(MX+5,-1); vb b(MX-1,true); for(ll i=2;i<=sqrt(MX);i++)if(b[i-2]){ for(ll j=2;i*j<=MX;j++){ if(b[i*j-2])f[i*j]=i; b[i*j-2]=false; } } rep(i,MX-1)if(b[i])primenumbers.pb(i+2); } bool is_prime(ll n){ if(n<=1)return false; REP(i,2,sqrt(n)+1)if(n%i==0)return false; return true; } vp fastbunkai(ll n){ //nがMX以下ならO(logn), 大きいとO(sqrt(n)) vp res; if(n<=1)return res; if(n>MX){ for(ll i:primenumbers){ if(n%i)continue; res.pb(i,0); while(n%i==0){res.back().se++;n/=i;} } } else{ while(f[n]!=-1){ ll k=f[n]; res.pb(k,0); while(n%k==0){res.back().se++;n/=k;} } } if(n!=1)res.pb(n,1); return res; } int main(){ ll n,m;cin>>n>>m; vp v(m);rep(i,m)cin>>v[i].se>>v[i].fi; ll mx=0; sort(all(v)); ll cnt=n; for(auto x:v){ if(mx>=x.se)continue; mx=x.fi; cnt--; } out(cnt); }