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#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
//mt19937 mrand(random_device{}()); 
const ll mod=1000000007;
//int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=1010000;
int n,k;
int cnt[N][5];
int main() {
	scanf("%d%d",&n,&k);
	rep(i,0,k) {
		int l,r,c;
		scanf("%d%d%d",&l,&r,&c);
		cnt[l][c]++; cnt[r+1][c]--;
	}
	rep(i,1,4) rep(j,1,n+1) cnt[j][i]+=cnt[j-1][i];
	int ans=0;
	rep(i,1,n+1) if (cnt[i][1]>0&&cnt[i][2]>0&&cnt[i][3]==0) {
		ans++;
	}
	printf("%d\n",ans);
}