#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
#define show(x,y) cout << y << " " << #x << endl;
#define show2(x,y,i,j) cout << y << " " << #x << " " << j << " " << #i << endl;
#define show3(x,y,i,j,p,q) cout << y << " " << #x << " " << j << " " << #i << " " << q << " " << #p << endl;
#define show4(x,y) for(auto it:y) cout << it << " "; cout << #x << endl;
typedef pair<int,int>pii;
typedef array<int,4>pi2;
mt19937_64 rng(chrono::system_clock::now().time_since_epoch().count());
void solve(){
int n,m;
cin >> n >> m;
pii arr[m];
int temp,temp2,temp3;
for(int x=0;x<m;x++){
cin >> temp >> temp2 >> temp3;
temp--;
temp2--;
if(temp>temp2) swap(temp,temp2);
arr[x]={temp,temp2};
}
int mini=1e15;
for(int x=0;x<(1<<m);x++){
int dp[n+5];
memset(dp,0,sizeof(dp));
for(int y=0;y<m;y++){
if(x&(1<<y)){
int cur=arr[y].second;
while(cur!=arr[y].first){
dp[cur]++;
cur=(cur+1)%n;
}
}
else{
int cur=arr[y].first;
while(cur!=arr[y].second){
dp[cur]++;
cur=(cur+1)%n;
}
}
}
int maxi=0;
for(int x=0;x<n;x++){
maxi=max(maxi,dp[x]);
}
mini=min(mini,maxi);
}
cout << mini;
}
int32_t main(){
ios::sync_with_stdio(0);
cin.tie(0);
int t=1;
//cin >> t;
//freopen("hand.txt","r",stdin);
while(t--){
solve();
}
}
