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#include <bits/stdc++.h>
#ifdef SIO
#define dbg(name) cerr << #name ": " << (name) << "\t"
#define nl cerr<<endl
#else
#define dbg(name)
#define nl
#endif
#define st first
#define nd second
#define pb push_back
#define rep(i,begin,end) for(__typeof(end) i = begin; i <= end; i++)
using namespace std;
using ll = long long;
using pii = pair<int,int>;
const ll nax = 1e18+33;

struct event {
    int kol[5];
    event() {
        rep(i,1,3) {
            kol[i] = 0;
        }
    }
};

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int n,m;
    cin >> n >> m;
    vector<event> v(n+3); // 1 zolty, 2 niebieski, 3 czerwony
    rep(i,1,m) {
        int l,r,k;
        cin >> l >> r >> k;
        v[l].kol[k]++;
        v[r+1].kol[k]--;
    }
    int akt[4], ans = 0;
    rep(i,1,3) akt[i] = 0;
    
    rep(i,1,n) {
        rep(j,1,3) {
            akt[j] += v[i].kol[j];
        }
        if(akt[1] && akt[2] && !akt[3])
            ans++;
    }
    
    cout << ans << endl;
}