#include <bits/stdc++.h>
using namespace std;
int c[2000000],n,m,x,y,z,sum[2000000],maxx=-1;
int main(){
    ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	cin>>n>>m;
	for(int i=1;i<=m;i++){
		int k=0;
		cin>>x>>y>>z;
		c[x]++;
		c[y+1]--;
		for(int j=1;j<=n;j++){
			sum[i]=sum[i-1]+c[i];
		}
		for(int i=1;i<=n;i++){
			k+=sum[i];
		}
		maxx=max(k,maxx);
	}
	if(maxx%36==0){
		cout<<maxx/36;
	}else{
		cout<<maxx/36+1;
	}
	return 0;
}

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

NCAyCjEgMiAzNgo0IDMgMzY=

4 2
1 2 36
4 3 36