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

int main() {
    int n,m;
    cin >> n >> m;
    vector<vector<int>> start(n+1, vector<int>(4)), end(n+1, vector<int>(4));
    
    for(int i = 0; i < m; i++) {
        int s, e, color;
        cin >> s >> e >> color;
        start[s][color]++;
        end[e][color]++;
    }
    
    int res = 0;
    vector<int> colors(4);
    for(int i = 1; i <= n; i++) {        
        for(int j = 1; j <= 3; j++) {
            colors[j] += start[i][j];
        }
        if(colors[1] > 0 && colors[2] > 0 && colors[3] == 0) {
            res++;
        }
        for(int j = 1; j <= 3; j++) {
            colors[j] -= end[i][j];
        }
    }
    cout << res << endl;
}