#include "bits/stdc++.h"
// Begin Header {{{
#define all(x) (x).begin(), (x).end()
#define rep(i, s, n) for (i64 i = (s), i##_limit = (n); i < i##_limit; ++i)
#define repr(i, s, t) for (i64 i = (s), i##_limit = (t); i >= i##_limit; --i)
#define var(type, ...) \
    type __VA_ARGS__;  \
    read(__VA_ARGS__);
#ifndef DBG
#define dump(...)
#endif
using namespace std;
using i64 = int_fast64_t;
using pii = pair<i64, i64>;
template <class T, class U>
inline bool chmax(T &a, const U &b) {
    return b > a && (a = b, true);
}
template <class T, class U>
inline bool chmin(T &a, const U &b) {
    return b < a && (a = b, true);
}
constexpr int INF = 0x3f3f3f3f;
constexpr i64 LINF = 0x3f3f3f3f3f3f3f3fLL;

template <class T>
inline vector<T> makeV(const T &initValue, size_t sz) {
    return vector<T>(sz, initValue);
}

template <class T, class... Args>
inline auto makeV(const T &initValue, size_t sz, Args... args) {
    return vector<decltype(makeV<T>(initValue, args...))>(
        sz, makeV<T>(initValue, args...));
}

template <class T>
inline istream &operator>>(istream &is, vector<T> &vec) {
    for (auto &e : vec) is >> e;
    return is;
}

inline void read() {}

template <class Head, class... Tail>
inline void read(Head &head, Tail &... tail) {
    cin >> head;
    read(tail...);
}

inline void print() { cout << "\n"; }

template <class Head, class... Tail>
inline void print(Head &&head, Tail &&... tail) {
    cout << head;
    if (sizeof...(tail)) cout << ' ';
    print(forward<Tail>(tail)...);
}

template <class T>
inline ostream &operator<<(ostream &os, const vector<T> &vec) {
    static constexpr const char *delim[] = {" ", ""};
    for (const auto &e : vec) os << e << delim[&e == &vec.back()];
    return os;
}

template <class Container>
struct Rev {
    Container &x_;
    inline Rev(Container &x) : x_(x) {}
    inline auto begin() { return rbegin(x_); }
    inline auto end() { return rend(x_); }
};
// }}} End Header

template <class T>
struct FenwickTree {  // {{{
    vector<T> dat;
    const size_t SIZE_POW2;

    explicit FenwickTree(int size)
        : dat(size + 5, 0), SIZE_POW2(1 << (__lg(size + 5) + 1)) {}

    inline void add(int i, const T &v) {
        for (++i; i < dat.size(); i += i & -i) dat[i] += v;
    }

    inline T sum(int i) const {
        T s = 0;
        for (++i; i > 0; i -= i & -i) s += dat[i];
        return s;
        ;
    }

    inline T sum(int s, int t) const {
        if (s > t) swap(s, t);
        return sum(t) - sum(s - 1);
    }

    inline int lower_bound(T v) const {
        if (v <= 0) return 0;
        int i = 0;
        for (int w = SIZE_POW2; w > 0; w >>= 1) {
            if (i + w < dat.size() && dat[i + w] < v) {
                v -= dat[i + w];
                i += w;
            }
        }
        return i;
    }
};  // }}}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    var(int, N, M);
    vector<pair<int, int>> ps(M);
    rep(i, 0, M) {
        var(int, s, t);
        --s, --t;
        ps.emplace_back(t, s);
    }

    sort(all(ps));

    FenwickTree<int> ft(N);
    rep(i, 0, N - 1) { ft.add(i, 1); }

    int cnt = 0;
    for (const auto &e : ps) {
        const int s = e.second;
        const int t = e.first;
        if (ft.sum(s, t - 1) == t - s) {
            ft.add(t - 1, -1);
            ++cnt;
        }
    }

    print(cnt);

    return 0;
}


Measured memory_bytes: 2160