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#pragma GCC optimize("Ofast")
//#pragma GCC target ("avx2")
//#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include<bits/stdc++.h>
//#include <ext/pb_ds/assoc_container'.',hpp>
//#include <ext/pb_ds/tree_policy'.',hpp>
//typedef tree < int , null_type, less <int>, rb_tree_tag, tree_order_statistics_node_update> TREE;
#define ll long long
#define ull unsigned long long int
#define pb push_back
#define mp make_pair
#define vi vector<int>
#define pii pair<int,int>
#define pss pair<short,short>
#define pld pair<long double,long double >
#define ld long double
#define piii  pair<pii,int>
#define vii vector<pair<int,int> >
#define st first
#define nd second
#define pll pair<ll,ll>
#define speed ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define M_PI 3.14159265358979323846
#define int long long
const int mod=1000000007;
//const int mod=1009;
//const int mod=998244353;
const int inf=1000000009;
const long long INF=1000000000000000009;
const long long big=1000000000000000;
const long double eps=0.000000000000000000001;
using namespace std;

int T[1000005][3];
int L[3];
void solve()
{
    int n,m;
    cin>>n>>m;
    for(int i=1;i<=m;i++)
    {
        int a,b,c;
        cin>>a>>b>>c;
        c--;
        T[a][c]++;
        T[b+1][c]--;
    }
    int wynik=0;
    for(int i=1;i<=n;i++)
    {
        int ile=0;
        for(int j=0;j<3;j++)
        {
            L[j]+=T[i][j];
            if(L[j]>0)
            {
                if(j<2)
                    ile++;
                else
                    ile--;
                
            }
           // cout<<i<<" "<<j<<" "<<L[j]<<endl;
        }
        if(ile==2)
            wynik++;
    }
    cout<<wynik;
}




int32_t main(){
    speed
    int t = 1;
    //cin >> t;
    while(t--){
    	solve();
    }
    return 0;
}