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

int main()
{   
    ios_base::sync_with_stdio(false);

    int n, m;
    cin >> n >> m;
    
    auto a = vector<vector<int>>(n+2, vector<int>(3, 0));
    
    while (m--) {
        int le, r, k;
        cin >> le >> r >> k;
        a[le][k-1] += 1;
        a[r+1][k-1] -= 1;
    }
    
    for (int i = 1; i <= n; ++i) {
        for (int j = 0; j < 3; ++j) {
            a[i][j] += a[i-1][j];
        }
    }
    
    int ans = 0;
    for (int i = 1; i <= n; ++i) {
        if (a[i][0] > 0 && a[i][1] > 0 && a[i][2] == 0) { ++ans; }
    }
    
    cout << ans << '\n';
}