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#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <vector>
#include <algorithm>
using namespace std;

struct point{
    int x;
    int y;
};
vector <point> y ;
vector <point> b ;
vector <point> r ;
int tab[1000005];
bool cmp(point a, point b){

    if( a.x>b.x){
        return true;
    }
    if(a.x==b.x && a.y>b.y){
        return true;
    }
    return false;
}
int main()
{
    int n,m;
    scanf("%d %d", &n, &m);


    int l,ri,k;
    for(int i=0;i<m;i++){
        scanf("%d %d %d", &l, &ri, &k);
        point a;
        a.x = l;
        a.y = ri;
        if( k == 1){
            y.push_back(a);
        }
        if( k == 2){
            b.push_back(a);
        }
        if( k == 3){
            r.push_back(a);
        }
    }
    //cout<<"----"<<endl;
    sort(y.begin(), y.end(), cmp);
    sort(b.begin(), b.end(), cmp);
    sort(r.begin(), r.end(), cmp);
    //point y = NULL;
    int maxi =-1;
    while(!y.empty()){
        point c = y.back();
        y.pop_back();
        if( maxi>c.x){
            c.x = maxi;
        }
        for(int i =c.x; i<=c.y;i++){
            tab[i]= 1;
        }
        if(c.y >maxi){
            maxi = c.y;
        }
    }

    maxi =-1;
    while(!b.empty()){
        point c = b.back();
        b.pop_back();
        if( maxi>c.x){
            c.x = maxi;
        }
        for(int i =c.x; i<=c.y;i++){
            tab[i]|= 1<<1;
        }
        if(c.y >maxi){
            maxi = c.y;
        }
    }

    maxi =-1;
    while(!r.empty()){
        point c = r.back();
        r.pop_back();
        if( maxi>c.x){
            c.x = maxi;
        }
        for(int i =c.x; i<=c.y;i++){
            tab[i]|= 1<<2;
        }
        if(c.y >maxi){
            maxi = c.y;
        }
    }
    int result = 0;
    for(int i =0; i<n;i++){
        if( tab[i]==3){
            result++;
        }
    }
    printf("%d\n",result);

    return 0;
}