#include <bits/stdc++.h>
using namespace std;
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int n, m;
cin >> n >> m;
pair<int, int> ranges[m];
int ar[n];
for(int i = 0; i<=n; i++){
ar[i] = 0;
}
bool used[m];
for(int i = 0; i<m; i++){
used[i] = false;
int a, b;
cin >> a >> b;
a--;
b--;
int c;
cin >> c;
if(a>b){
swap(a,b);
}
a++;
ranges[i] = make_pair(a,b);
// cout << "! " << a << " " << b << endl;
for(int j = a; j<=b; j++){
ar[j]++;
}
}
while(true){
bool did = false;
for(int i = 0; i<m; i++){
int outmax = 0;
int inmax = 0;
// cout << "A " << i << endl;
if(used[i]){
continue;
}
// cout << "B " << i << endl;
for(int j = 0; j<n; j++){
if(j>=ranges[i].first && j<=ranges[i].second){
inmax = max(inmax,ar[j]);
}
else{
outmax = max(outmax,ar[j]);
}
}
// cout << "X " << i << " " << inmax << " " << outmax << endl;
if(inmax-1 <= outmax){
continue;
}
// cout << "DOING " << i << endl;
did = true;
// used[i] = true;
for(int j = 0; j<n; j++){
if(j>=ranges[i].first && j<=ranges[i].second){
ar[j]--;
}
else{
ar[j]++;
}
}
}
if(!did){
break;
}
}
int ans = 0;
for(int i = 0; i<n; i++){
ans = max(ar[i],ans);
}
cout << ans << endl;
}
