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#include <bits/stdc++.h>
using namespace std;
#define bit(n, i) ((n>>i) & 1)
#define fi first
#define se second
#define pb push_back
#define cat(x) cerr << #x " = " << x << "\n"
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using ld = long double;

const int N = 1e6+9;
int cnt[N][3];

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);

    int n, m; cin >> n >> m;
    for(int i = 1; i <= m; ++i) {
        int l, r, k; cin >> l >> r >> k;
        cnt[l][k-1]++;
        cnt[r+1][k-1]--;
    }
    int res = 0;
    for(int i = 1; i <= n; ++i) {
        cnt[i][0] += cnt[i-1][0];
        cnt[i][1] += cnt[i-1][1];
        cnt[i][2] += cnt[i-1][2];
        if(cnt[i][0] >= 1 && cnt[i][1] >= 1 && cnt[i][2] == 0)
            res++;
    }
    cout << res;

    return 0;
}