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#include <cstdio>
#include <cmath>
#include <iostream>
#include <algorithm>
#include <queue>
#include <list>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <cstring>
#include <cassert>
#include <limits.h>

using namespace std;

#define ST first
#define ND second
#define MP make_pair
#define PB push_back

typedef long long LL;
typedef long double LD;

typedef vector<int> VI;
typedef pair<int,int> PII;
#define REP(i,n) for(int i=0;i<(n);i++)
#define FOR(i,a,b) for(VAR(i,a);i<=(b);++i)
#define FORD(i,a,b) for(VAR(i,a);i>=(b);--i)
#define FORE(a,b) for(VAR(a,(b).begin());a!=(b).end();++a)
#define VAR(a,b) __typeof(b) a=(b)
#define SIZE(a) ((int)((a).size()))
#define ALL(x) (x).begin(),(x).end()
#define CLR(x,a) memset(x,a,sizeof(x))
#define ZERO(x) memset(x,0,sizeof(x))
#define S(t,i) scanf("%" ## t, &i)
#define SI(i) scanf("%d", &i)

const int INF=INT_MAX;
const int MAXN=1000000+5;

struct operation {
    int t;
    int c;
};

int compareOperations(const void * a, const void * b)
{
  return ((operation *)a)->t - ((operation*)b)->t;
}

int n, m;

int colors[4];
operation startOperations[MAXN];
operation endOperations[MAXN];
int result;

int main() {
    //ios_base::sync_with_stdio(0);
    
    SI(n);
    SI(m);
    
    REP(i, m) {
        scanf("%d %d %d", &startOperations[i].t, &endOperations[i].t, &startOperations[i].c);
        endOperations[i].c = startOperations[i].c;
    }
    qsort(startOperations, m, sizeof(startOperations[0]), compareOperations);
    qsort(endOperations, m, sizeof(endOperations[0]), compareOperations);
//    REP(i,m) {
//        printf("%d ", startOperations[i].t);
//    }
//    printf("\n");
//    REP(i,m) {
//        printf("%d ", endOperations[i].t);
//    }
//    printf("\n");
    
    endOperations[m].t = INT_MAX;
    startOperations[m].t = INT_MAX;
    
    int si = 0, ei = 0;
    bool wasGreen = false;
    int prevTime = 1;
    while (si < m || ei < m) {
        int currTime = min(endOperations[ei].t, startOperations[si].t);
        if (wasGreen && (currTime - prevTime - 1) > 0) {
            result += (currTime - prevTime - 1);
        }
        prevTime = currTime;
        
        while (currTime == startOperations[si].t) {
            colors[startOperations[si].c]++;
            si++;
        }
        if ((colors[1] > 0) && (colors[2] > 0) && (colors[3] == 0)) {
            result++;
        }
            
        while (currTime == endOperations[ei].t) {
            colors[endOperations[ei].c]--;
            ei++;
        }
        wasGreen = (colors[1] > 0) && (colors[2] > 0) && (colors[3] == 0);
    }
    
    printf("%d\n", result);
    return 0;
}