//#pragma GCC optimize("Ofast,unroll-loops")
#include <bits/stdc++.h>
using namespace std;
typedef long long llo;
#define mp make_pair
#define pb push_back
#define a first
#define b second
#define endl '\n'
int n,m;
int aa[200001];
int bb[200001];
int cc[200001];
int co[200001];
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin>>n>>m;
for(int i=0;i<m;i++){
cin>>aa[i]>>bb[i]>>cc[i];
aa[i]--;
bb[i]--;
}
int ans=m;
for(int i=0;i<(1<<m);i++){
for(int j=0;j<n;j++){
co[j]=0;
}
for(int j=0;j<m;j++){
if(i&(1<<j)){
int cur=aa[j];
while(cur!=bb[j]){
co[cur]++;
cur=(cur+1)%n;
}
}
else{
int cur=bb[j];
while(cur!=aa[j]){
co[cur]++;
cur=(cur+1)%n;
}
}
}
int ma=0;
for(int j=0;j<n;j++){
ma=max(ma,co[j]);
}
ans=min(ans,ma);
}
cout<<ans<<endl;
return 0;
}
