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// Artur Kraska, II UWr

#include <bits/stdc++.h>

#define forr(i, n)                  for(int i=0; i<n; i++)
#define FOREACH(iter, coll)         for(auto iter = coll.begin(); iter != coll.end(); ++iter)
#define FOREACHR(iter, coll)        for(auto iter = coll.rbegin(); iter != coll.rend(); ++iter)
#define lbound(P,R,PRED)            ({typeof(P) X=P,RRR=(R), PPP = P; while(PPP<RRR) {X = (PPP+(RRR-PPP)/2); if(PRED) RRR = X; else PPP = X+1;} PPP;})
#define testy()                     int _tests; scanf("%d", &_tests); FOR(_test, 1, _tests)
#define CLEAR(tab)                  memset(tab, 0, sizeof(tab))
#define CONTAIN(el, coll)           (coll.find(el) != coll.end())
#define FOR(i, a, b)                for(int i=a; i<=b; i++)
#define FORD(i, a, b)               for(int i=a; i>=b; i--)
#define MP                          make_pair
#define PB                          push_back
#define ff                          first
#define ss                          second
#define deb(X)                      X;

#define M 1000000007
#define INF 1000000007LL

using namespace std;

int n, m, l, r, id, ile[4], il[4][1000007];

int main()
{
    scanf("%d %d", &n, &m);
    forr(i, m)
    {
        scanf("%d %d %d", &l, &r, &id);
        il[id][l]++;
        il[id][r+1]--;
    }

    int res = 0;
    FOR(i, 1, n)
    {
        FOR(c, 1, 3)
            ile[c] += il[c][i];
        if(ile[1] > 0 && ile[2] > 0 && ile[3] == 0)
            res++;
    }
    printf("%d\n", res);

    return 0;
}