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//#pragma comment(linker, "/stack:200000000")
#ifndef LOCAL
#pragma GCC optimize("O3")
#endif
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>

using namespace std;

#define sim template < class c
#define ris return * this
#define dor > debug & operator <<
#define eni(x) sim > typename \
  enable_if<sizeof dud<c>(0) x 1, debug&>::type operator<<(c i) {
sim > struct rge { c b, e; };
sim > rge<c> range(c i, c j) { return rge<c>{i, j}; }
sim > auto dud(c* x) -> decltype(cerr << *x, 0);
sim > char dud(...);
struct debug {
#ifdef LOCAL
~debug() { cerr << endl; }
eni(!=) cerr << boolalpha << i; ris; }
eni(==) ris << range(begin(i), end(i)); }
sim, class b dor(pair < b, c > d) {
  ris << "(" << d.first << ", " << d.second << ")";
}
sim dor(rge<c> d) {
  *this << "[";
  for (auto it = d.b; it != d.e; ++it)
	*this << ", " + 2 * (it == d.b) << *it;
  ris << "]";
}
#else
sim dor(const c&) { ris; }
#endif
};
#define var(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "

#define pb push_back
#define mp make_pair
#define st first
#define nd second
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define un(x) x.erase(unique(ALL(x)),x.end())
#define REP(i,x,v)for(int i=x;i<=v;i++)
#define REPD(i,x,v)for(int i=x;i>=v;i--)
#define FOR(i,v)for(int i=0;i<v;i++)
#define TRAV(i,v)for(auto &i:(v))
#define REMIN(x,v) x=min(x,v);
#define REMAX(x,v) x=max(x,v);

mt19937_64 rng(134569);
int rd(int l, int r) {return uniform_int_distribution<int>(l, r)(rng);}

using ll=long long;
using pii=pair<int,int>;
using pll=pair<ll,ll>;
using vi=vector<int>;
using vll=vector<ll>;
const int MOD=1e9+7;//998244353;

int tot[3][1<<20];
int s[3];

int main()
{
	ios_base::sync_with_stdio(0);cin.tie(0);
	cout << fixed << setprecision(11);
	cerr << fixed << setprecision(6);

  int n,m;cin>>n>>m;
  FOR(i,m) {
    int a,b,c;
    cin>>a>>b>>c;
    c--;
    tot[c][a]+=1;
    tot[c][b+1]-=1;
  }
  int cnt=0;
  REP(i,1,n) {
    FOR(c,3) s[c]+=tot[c][i];
    if (s[0]>0 && s[1]>0 && s[2]==0) cnt++;
  }
  cout<<cnt<<"\n";
  return 0;
}