#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<queue>
#include<map>
#include<math.h>
#include<iomanip>
#include<set>
#include<numeric>
#include<cstring>
#include<cstdio>
#include<functional>
#include<bitset>
#include<limits.h>
#include<cassert>
#include<iterator>
#include<complex>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<time.h>
#include<random>
#include<array>
using namespace std;
using ll = long long;
#define rep(i, a, b) for(int i = a; i < b; i++)
#define rrep(i, a, b) for(int i = b - 1; i >= a; i--)
#define ALL(a) a.begin(), a.end()
using pii = pair<int,int>;
using piii = pair<pii,int>;
using pll = pair<long long, long long>;
using plll = pair<pll, long long>;
// #pragma GCC optimize("Ofast")
#define pcnt __builtin_popcount
#define buli(x) __builtin_popcountll(x)
#define pb push_back
#define mp make_pair
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
#define isSquare(x) (sqrt(x)*sqrt(x) == x)
template<class T>bool chmax(T &a, const T &b) {if(a<b){a = b; return 1;} return 0; };
template<class T>bool chmin(T &a, const T &b) {if(a>b){a = b; return 1;} return 0; };
inline void in(void){return;}
template <typename First, typename... Rest> void in(First& first, Rest&... rest){cin >> first;IN(rest...);return;}
inline void out(void){cout << "\n";return;}
template <typename First, typename... Rest> void out(First first, Rest... rest){cout << first << " ";OUT(rest...);return;}
const double EPS = 1e-9;
const int mod = 1e9 + 7;
const int INF = 1e9;
const long long INFLL = 1e18;
void iosetup() {
    cin.tie(nullptr);ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
}
template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 >& p) {
    os << p.first << " " << p.second;
    return os;
}
template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
    is >> p.first >> p.second;
    return is;
}
template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
    for(int i = 0; i < (int) v.size(); i++) {
        os << v[i] << (i + 1 != v.size() ? " " : "");
    }
    return os;
}
template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
    for(T &in : v) is >> in;
    return is;
}
template <typename T> void Exit(T first){cout << first << endl;exit(0); };
template< int mod > struct ModInt {
    int x; ModInt() : x(0) {}
    ModInt(int64_t y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
    ModInt &operator+=(const ModInt &p) {if((x += p.x) >= mod) x -= mod;return *this;}
    ModInt &operator-=(const ModInt &p) {if((x += mod - p.x) >= mod) x -= mod;return *this;}
    ModInt &operator*=(const ModInt &p) {x = (int) (1LL * x * p.x % mod);return *this;}
    ModInt &operator/=(const ModInt &p) {*this *= p.inverse();return *this;}
    ModInt operator-() const { return ModInt(-x); }
    ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; }
    ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; }
    ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; }
    ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; }
    bool operator==(const ModInt &p) const { return x == p.x; }
    bool operator!=(const ModInt &p) const { return x != p.x; }
    ModInt inverse() const {int a = x, b = mod, u = 1, v = 0, t;
    while(b > 0) { t = a / b; swap(a -= t * b, b); swap(u -= t * v, v); }return ModInt(u);}
    ModInt pow(int64_t n) const {ModInt ret(1), mul(x); while(n > 0) {if(n & 1) ret *= mul;mul *= mul;n >>= 1;}return ret;}
    friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x;}
    friend istream &operator>>(istream &is, ModInt &a) { int64_t t; is >> t; a = ModInt< mod >(t); return (is); }
    static int get_mod() { return mod; }
}; using modint = ModInt< mod >;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

template< typename Monoid, typename OperatorMonoid = Monoid >
struct LazySegmentTree
{
  using F = function< Monoid(Monoid, Monoid) >;
  using G = function< Monoid(Monoid, OperatorMonoid) >;
  using H = function< OperatorMonoid(OperatorMonoid, OperatorMonoid) >;
  using P = function< OperatorMonoid(OperatorMonoid, int) >;

  int sz;
  vector< Monoid > data;
  vector< OperatorMonoid > lazy;
  const F f;
  const G g;
  const H h;
  const P p;
  const Monoid M1;
  const OperatorMonoid OM0;


  LazySegmentTree(int n, const F f, const G g, const H h, const P p,
                  const Monoid &M1, const OperatorMonoid OM0)
      : f(f), g(g), h(h), p(p), M1(M1), OM0(OM0)
  {
    sz = 1;
    while(sz < n) sz <<= 1;
    data.assign(2 * sz, M1);
    lazy.assign(2 * sz, OM0);
  }

  void set(int k, const Monoid &x)
  {
    data[k + sz] = x;
  }

  void build()
  {
    for(int k = sz - 1; k > 0; k--) {
      data[k] = f(data[2 * k + 0], data[2 * k + 1]);
    }
  }

  void propagate(int k, int len)
  {
    if(lazy[k] != OM0) {
      if(k < sz) {
        lazy[2 * k + 0] = h(lazy[2 * k + 0], lazy[k]);
        lazy[2 * k + 1] = h(lazy[2 * k + 1], lazy[k]);
      }
      data[k] = g(data[k], p(lazy[k], len));
      lazy[k] = OM0;
    }
  }

  Monoid update(int a, int b, const OperatorMonoid &x, int k, int l, int r)
  {
    propagate(k, r - l);
    if(r <= a || b <= l) {
      return data[k];
    } else if(a <= l && r <= b) {
      lazy[k] = h(lazy[k], x);
      propagate(k, r - l);
      return data[k];
    } else {
      return data[k] = f(update(a, b, x, 2 * k + 0, l, (l + r) >> 1),
                         update(a, b, x, 2 * k + 1, (l + r) >> 1, r));
    }
  }

  Monoid update(int a, int b, const OperatorMonoid &x)
  {
    return update(a, b, x, 1, 0, sz);
  }


  Monoid query(int a, int b, int k, int l, int r)
  {
    propagate(k, r - l);
    if(r <= a || b <= l) {
      return M1;
    } else if(a <= l && r <= b) {
      return data[k];
    } else {
      return f(query(a, b, 2 * k + 0, l, (l + r) >> 1),
               query(a, b, 2 * k + 1, (l + r) >> 1, r));
    }
  }

  Monoid query(int a, int b)
  {
    return query(a, b, 1, 0, sz);
  }

  Monoid operator[](const int &k)
  {
    return query(k, k + 1);
  }
};


int main(){
    iosetup();
    int N, M; cin >> N >> M;
    auto f = [](ll a, ll b){ return max(a, b);};
    auto g = [](ll a, ll b){ return a + b; };
    auto h = [](ll a, ll b){ return a + b; };
    auto p = [](ll a, ll b){ return a; };
    LazySegmentTree<ll> seg(N+1,f, g, h, p, 0, 0);
    vector<piii> P(M);
    rep(i, 0, M){
        int l, r, a; cin >> l >> r >> a;
        P[i] = piii(pii(r, l), a);
    }
    sort(ALL(P));
    int idx = 0;
    // seg.update(0, 1, 0);
    rep(i, 1, N + 1){
        ll MA = seg.query(0, i);
        seg.update(i, i + 1, MA);
        while(idx < M and P[idx].first.first == i){
            ll l = P[idx].first.second;
            ll a = P[idx].second;
            seg.update(l, i + 1, a);
            idx++;
            // cerr << idx << " " <<  seg.query(1, N + 1) << endl;
        }
    }
    cout << seg.query(0, N + 1) << endl;


    return 0;
}

Measured memory_bytes: 10880