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#include <bits/stdc++.h>
using namespace std;

#define debug if(0)
#define pb push_back
#define mp make_pair
#define ff first
#define ss second

#define ZAK 2097155

int n, m, l, r, k, R;
bool tree[ZAK][4];

void insert(int x, int pp, int pk, int zp, int zk, int k) {
    if (pk < zp || zk < pp) {
        return;
    }
    
    if (zp <= pp && pk <= zk) {
        tree[x][k] = true;
        return;
    }
    
    int sr = (pp + pk) / 2;
    
    insert(x * 2, pp, sr, zp, zk, k);
    insert(x * 2 + 1, sr + 1, pk, zp, zk, k);
}

int main() {

    cin >> n >> m;

    R = 1;
    while (R < n) {
        R <<= 1;
    }
    
    for (int i = 1; i <= m; ++i) {
        cin >> l >> r >> k;
        insert(1, 1, R, l, r, k);
    }
    
    for (int i = 1; i < R; ++i) {
        for (int j = 1; j <= 3; ++j) {
            tree[i * 2][j] |= tree[i][j];
            tree[i * 2 + 1][j] |= tree[i][j];
        }
    }
    
    int wynik = 0;
    
    for (int i = 1; i <= n; ++i) {
        if (tree[i + R - 1][1] && tree[i + R - 1][2] && !tree[i + R - 1][3]) {
            ++wynik;
        }
    }
    
    printf ("%d\n", wynik);

    return 0;
}