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#include <bits/stdc++.h>

#define FOR(i, a, b) for(int i = a; i<b; ++i)
#define FR(a, b) for(int i = a; i>=b;--i)
#define _upgrade cin.tie(0); ios_base::sync_with_stdio(0)
#define pb push_back
#define mp make_pair
#define INF 1e9

using namespace std;

typedef long long ll;
typedef double db;
typedef unsigned long long ull;
typedef pair<int, int> iPair;

const int MAX = 1e6 + 2;
const int M = 1e9 +7;

int n, m, p1[MAX], p2[MAX], p3[MAX], s1, s2, s3;
int main()
{
    _upgrade;
    cin>>n>>m;
    while(m--)
    {
        int l, r, k;
        cin>>l>>r>>k;
        if(k == 1)
        {
            p1[r+1] -= 1;
            p1[l] += 1;
        }
        else if(k == 2)
        {
            p2[r+1] -= 1;
            p2[l] += 1;
        }
        else
        {
            p3[r+1] -= 1;
            p3[l] += 1;
        }
    }
    FOR(i, 1, n+1)
    {
        s1 += p1[i];
        s2 += p2[i];
        s3 += p3[i];
        p1[i] = min(1, s1);
        p2[i] = min(1, s2);
        p3[i] = min(1, s3);
    }
//    FOR(i, 1, n+1)
//        cout<<p1[i]<<" ";
//    cout<<"\n";
//     FOR(i, 1, n+1)
//        cout<<p2[i]<<" ";
//    cout<<"\n";
//     FOR(i, 1, n+1)
//        cout<<p3[i]<<" ";
//    cout<<"\n";
    int res = 0;
    FOR(i, 1, n+1)
        if(p1[i] && p2[i] && !p3[i])
            res++;
    cout<<res;
}