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#pragma GCC optimize ("Ofast")
#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define FOR(i, a, b) for (int i=(a); i<(b); i++)
#define FORD(i, a, b) for (int i=(a); i>(b); i--)
#define PPC(x) __builtin_popcount(x)
#define MSB(x) (63 - __builtin_clzll(x))
#define SZ(x) ((int)(x).size())
#define HASK(S, x) (S.find(x) != S.end())
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define ithBit(m, i) ((m) >> (i) & 1)
#define ft first
#define sd second
#define kw(a) ((a) * (a))
#ifdef DEBUG
#include "debug.h"
#else
#define dbg(...) 0
#endif
using namespace std; 
  
template <typename T1, typename T2> inline void remax(T1& a, T2 b) { a = max(a, (T1)b);	}

const int maxN = 1 << 20;

int range[maxN][4];

void solve()
{
	int n, q;
	scanf ("%d%d", &n, &q);
	
	while (q--)
	{
		int a, b, k;
		scanf ("%d%d%d", &a, &b, &k);
		remax(range[a][k], b);
	}
	int res = 0, x[4] = {0, 0, 0, 0};
	
	FOR(i, 1, n+1)
	{
		FOR(s, 1, 4) remax(x[s], range[i][s]);
		res += i <= x[1] and i <= x[2] and i > x[3];
	}
	printf("%d\n", res);
}
 
int main()
{
	int t = 1;
	//scanf ("%d", &t);
	FOR(tid, 1, t+1)
	{
		//printf("Case #%d: ", tid);
		solve();
	}
	return 0;
}