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//#pragma comment(linker, "/stack:200000000")
//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//#pragma GCC optimize("unroll-loops")

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <fstream>
#include <sstream>
#include <set>
#include <map>
#include <vector>
#include <list>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <string>
#include <queue>
#include <bitset>		//UWAGA - w czasie kompilacji musi byc znany rozmiar wektora - nie mozna go zmienic
#include <cassert>
#include <iomanip>		//do setprecision
#include <ctime>
#include <complex>
#include <chrono>
#include<unordered_map>
using namespace std;

#define FOR(i,b,e) for(int i=(b);i<(e);++i)
#define FORQ(i,b,e) for(int i=(b);i<=(e);++i)
#define FORD(i,b,e) for(int i=(b)-1;i>=(e);--i)
#define REP(x, n) for(int x = 0; x < (n); ++x)
#define ALL(u) (u).begin(),(u).end()

#define ST first
#define ND second
#define PB push_back
#define MP make_pair
#define MT make_tuple
#define LL long long
#define ULL unsigned LL
#define LD long double

typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef tuple<int, int, int> TIII;
typedef vector<int> VI;

const double pi = 3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342;

const int MR = 1e6 + 10;

void fast_io() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}

int ile[3][MR];

int main()
{
    fast_io();

    int n, m;
    scanf("%d%d", &n, &m);
    REP(i, m)
    {
        int k, l, r;
        scanf("%d%d%d", &l, &r, &k); k--;
        ile[k][l]++;
        ile[k][r + 1]--;
    }

    int res = 0;
    FORQ(i, 1, n)
    {
        REP(k, 3)
            ile[k][i] += ile[k][i - 1];

        if (ile[0][i] && ile[1][i] && !ile[2][i])
            res++;
    }

    printf("%d\n", res);

    return 0;
}

// FOR GNU C++ use the following pattern:
// Uncomment the code below and change your main into main2
// It does not build in MS C++
// But it does increase the stack size from 256 MB on CF and uses GNU C++

//#include <Processthreadsapi.h>
//#include <iostream>
//#include <Synchapi.h>
//#include <windows.h>
//#include <process.h>
//
//DWORD WINAPI MyThreadFunction(LPVOID lpParam) {
//    main2(nullptr);
//    return 0;
//}
//int main() {
//    auto h = CreateThread(nullptr, 1024 << 20, MyThreadFunction, nullptr, STACK_SIZE_PARAM_IS_A_RESERVATION, nullptr);
//    WaitForSingleObject(h, INFINITE);
//}