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#include<bits/stdc++.h>
#include<chrono>
#define ff first
#define ss second
#define eb emplace_back
#define putchar putchar_unlocked
#define getchar getchar_unlocked
#define debug if(0)
using namespace std;
typedef long long int LL;
typedef long double LD;
typedef short int SH;

inline void readI(int *i)
{
	register int r=0;
	register char c=getchar();
	int z=1;
	if(c == '-')
	{
		z=-1;
	}
	while(c < '0' || c > '9')
	{
		c=getchar();
		if(c == '-')
		{
			z=-1;
		}
	}
	while(c >= '0' && c <= '9')
	{
		r=(r<<3)+(r<<1)+c-'0';
		c=getchar();
	}
	*i=(r*z);
}
inline void readUI(int *i)
{
	register int r=0;
	register char c=getchar();
	while(c < '0' || c > '9')
	{
		c=getchar();
	}
	while(c >= '0' && c <= '9')
	{
		r=(r<<3)+(r<<1)+c-'0';
		c=getchar();
	}
	*i=r;
}
inline void readLL(LL *l)
{
	register LL r=0;
	register char c=getchar();
	int z=1;
	if(c == '-')
	{
		z=-1;
	}
	while(c < '0' || c > '9')
	{
		c=getchar();
		if(c == '-')
		{
			z=-1;
		}
	}
	while(c >= '0' && c <= '9')
	{
		r=(r<<3)+(r<<1)+c-'0';
		c=getchar();
	}
	*l=(r*z);
}
inline void readULL(LL *l)
{
	register LL r=0;
	register char c=getchar();
	while(c < '0' || c > '9')
	{
		c=getchar();
	}
	while(c >= '0' && c <= '9')
	{
		r=(r<<3)+(r<<1)+c-'0';
		c=getchar();
	}
	*l=r;
}
inline void write(LL l)
{
	if(!l)
	{
		putchar(48);
	}
	else
	{
		if(l < 0)
		{
			l^=-1;
			++l;
			putchar(45);
		}
		int p=0,h[21];
		while(l)
		{
			++p;
			h[p]=(l%10)+48;
			l/=10;
		}
		for(int i=p+1; --i;)
		{
			putchar(h[i]);
		}
	}
}
inline void writeS(string s)
{
	int l=s.length();
	for(int i=0; i^l; ++i)
	{
		putchar(s[i]);
	}
}

int n,m,w,r=1,a,b,c,tree[2100007];
void insert(int x, int pp, int pk, int zp, int zk, int war)
{
	if(pp > zk || pk < zp)
	{
		return;
	}
	if(pp >= zp && pk <= zk)
	{
		tree[x]|=war;
		return;
	}
	int sr=(pp+pk)>>1;
	insert(x+x, pp, sr, zp, zk, war);
	insert(x+x+1, sr+1, pk, zp, zk, war);
}
int query(int x)
{
	int res=0;
	x+=r-1;
	while(x)
	{
		res|=tree[x];
		x>>=1;
	}
	return res;
}
int main()
{
	readUI(&n);
	readUI(&m);
	while(r < n)
	{
		r<<=1;
	}
	for(int i=0; i^m; ++i)
	{
		readUI(&a);
		readUI(&b);
		readUI(&c);
		insert(1, 1, r, a, b, 1<<(c-1));
	}
	for(int i=1; i<=n; ++i)
	{
		w+=(query(i) == 3);
	}
	write(w);
	return 0;
}