#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define pb emplace_back
#define AI(i) begin(i), end(i)
template<class T> bool chmin(T &a, T b) { return b < a && (a = b, true); }
template<class T> bool chmax(T &a, T b) { return a < b && (a = b, true); }
#ifdef KEV
#define DE(args...) kout("[ " + string(#args) + " ] = ", args)
void kout() { cerr << endl; }
template<class T, class ...U> void kout(T a, U ...b) { cerr << a << ' ', kout(b...); }
template<class T> void debug(T l, T r) { while (l != r) cerr << *l << " \n"[next(l)==r], ++l; }
#else
#define DE(...) 0
#define debug(...) 0
#endif
const int MAX_N = 300010;
int n, m;
int32_t main() {
ios_base::sync_with_stdio(0), cin.tie(0);
cin >> n >> m;
vector<tuple<int,int,int>> req(m);
for (auto &[l, r, c] : req) {
cin >> l >> r >> c;
if (l > r) swap(l, r);
--r;
assert(c == 1);
}
sort(AI(req));
int res = 0;
vector<int> sum(n + 1);
for (auto [l, r, c] : req) {
int a = 0, b = 0;
for (int i = 1;i <= n;++i) {
chmax((l<=i&&i<=r?a:b), sum[i]);
}
if (a < b) {
for (int i = l;i <= r;++i)
++sum[i];
}
else {
for (int i = 1;i < l;++i)
++sum[i];
for (int i = r+1;i <= n;++i)
++sum[i];
}
}
cout << *max_element(AI(sum)) << '\n';
}
