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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;}
int gcd(int a,int b) { return b?gcd(b,a%b):a;}
// head

const int N=1e6+5;

#define INF 0x3f3f3f3f

template<class T> inline void read(T &x) {
    x=0; int c=getchar(),f=1;
    for (;!isdigit(c);c=getchar()) if (c==45) f=-1;
    for (;isdigit(c);c=getchar()) (x*=10)+=f*(c-'0');
}
int n,m,l,r,k,pref[N][3],cur[3];

int solve() {
	int ans=0;
	rep(i,0,n) {
		rep(j,0,3) cur[j]+=pref[i][j];
		if (cur[0]>0&&cur[1]>0&&cur[2]==0) ans++;
	}
	return ans;
}

int main() {
	read(n); read(m);
	rep(i,0,m) {
		read(l); read(r); read(k);
		l--; k--;
		pref[l][k]++;
		pref[r][k]--;
	}
	printf("%d\n",solve());
}