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#include <cstdio>
#include <vector>
using namespace std;


int main() {
  int n, m;
	scanf("%d %d",&n, &m);
	vector<vector<int> > w(3, vector<int>(n+1));
	for (int i = 0; i < m; i++) {
		int l,r,k;
	  scanf("%d %d %d", &l, &r, &k);
		w[k-1][r]--;
		w[k-1][l-1]++;
	}
	vector<int> s(3);
	int ret = 0;
	for (int i = 0; i < n; i++) {
	  s[0] += w[0][i];
	  s[1] += w[1][i];
	  s[2] += w[2][i];
		if (s[0] > 0 && s[1] > 0 && s[2] == 0) {
			ret++;
			//printf("g %d\n", i+1);
		}
	}
	printf("%d\n", ret);
	return 0;
}