#include <bits/stdc++.h>

using namespace std;

#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
#define all(a) (a).begin(),(a).end()

typedef long long ll;
typedef long double ld;
typedef unsigned int uint;
typedef unsigned long long ull;

constexpr const int INT_INF=0x3f3f3f3f; // 1061109567
constexpr const ll LL_INF=0x3f3f3f3f3f3f3f3f; // 4557430888798830399
constexpr const double EPS=1e-9;

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

// INT
#define GCD(a, b) __gcd(a, b)
template <typename T> T LCM(T a, T b) {return a / GCD(a, b) * b;}
template <typename T> T EXTGCD(T a, T b, T& x, T& y) {
    T d = a;
    if (b != 0) {d=EXTGCD(b,a%b,y,x);y-=(a/b)*x;}
    else x=1,y=0;
    return d;
}
template <typename T> bool is_prime(T a) {
    for(int i=2;i*i<=a;i++)if(a%i==0)return true;
    return false;
}

// MOD
const ll MOD = 1000000000 + 7;
#define add(a, b) ((a % MOD) + (b % MOD)) % MOD
#define mul(a, b) ((a % MOD) * (b % MOD)) % MOD
#define sub(a, b) ((a % MOD) + MOD - (b % MOD)) % MOD
template <typename T> T mod_inverse(T a, T mod, bool prime){ // if mod is prime, "prime" is true.
    if(prime){
        T tmp=mod-2,now=a,res=1;while(tmp){if(tmp&1)res=mul(res,now);now=mul(now,now);tmp>>=1;}
        return res;
    }else{T x,y;EXTGCD(a,mod,x,y);return (mod+x%mod)%mod;}
}
#define divide(a, b) ((a % MOD) * (mod_inverse(b, MOD, true))) % MOD

// llのとき、数値の最後に"L"を付ける癖をつけよう.

//
//
//  　　┓　　　┏
//  　＊┗┓　┏┛
//  　　　┫　┣　＊
//  　┏┳┻━┻┳┓
//  　┗┫　　　┣┛
//  ＊　┣　　━┃　＊        Merry Christmas!!
//  　┏┛　　〃┃
//  　┃●　　　┣━┳┓
//  　┗┻┳━━┛　┣┛
//  　＊　┃┏┓┣┓┃
//WWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW

int n, m, k;
//int dist[310];

//void bfs(int start) {
//    dist[start] = 0;
//    queue < pair <int,int> > q;
//    q.push(mp(start, 0));
//    while (q.size()) {
//        int now = q.front().fi;
//        int nowd = q.front().se;
//        q.pop();
//        dist[now] = nowd;
//        for (int &i : v[now]) {
//            q.push(mp(i, nowd + 1));
//        }
//    }
//    for (int i = 0; i < n; i++) {
//        dist[i]++;
//    }
//}
int a[100001], b[100001];
vector < pair <int, int> > v;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.precision(10);
    cout << fixed;
#ifdef LOCAL_DEFINE
    FILE *stream1;
    //FILE *stream2;
    stream1 = freopen("/home/aim_cpo/ドキュメント/competitive/CLionProject/competitive/in.txt", "r", stdin);
    //stream2 = freopen("out.txt", "w", stdout);
    if (stream1 == nullptr) return 0;
    //if (stream2 == NULL) return 0;
#endif
    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int l, r; cin >> l >> r;
        v.push_back(mp(l, r));
    }
    sort(all(v));
    int left = v[0].fi;
    int right = v[0].se;
    int ans = 0;
    for (int i = 0; i < m; i++) {
        int nowl = v[i].fi;
        int nowr = v[i].se;
        if (left <= nowl && nowr <= right) {
            left = nowl;
            right = nowr;
        } else if (left <= nowl && nowl < right) {
            left = nowl;
        } else if (left < nowr && nowr <= right) {
            right = nowr;
        } else {
            ans++;
            left = nowl;
            right = nowr;
        }
    }
    cout << ans + 1 << endl;
#ifdef  LOCAL_DEFINE
    cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << "s.\n";
#endif
    return 0;
}

Measured memory_bytes: 1400