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#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define ST first
#define ND second
#define PB push_back
#define SIZE(a) ((int)a.size())

template<class T>
ostream& operator<<(ostream &stream, vector<T> &v) {
    stream << "[";
    for(auto elem : v) {
        stream << elem << ", ";
    }
    stream << "]";
    return stream;
}

int main() {
    ios_base::sync_with_stdio(0);
    int n, m;
    cin >> n >> m;
    vector<int> b[3];
    for(int i=0; i < 3; i++) {
        b[i].resize(n+1);
    }
    while(m--) {
        int le, ri, k;
        cin >> le >> ri >> k;
        k--;
        le--;
        ri--;
        b[k][le]++;
        b[k][ri+1]--;
    }
    vector<int> current(3);
    int res=0;
    for(int i=0; i < n; i++) {
        for(int j=0; j < 3; j++) {
            current[j]+=b[j][i];
        }
        if(current[0] > 0 && current[1] > 0 && current[2] == 0) {
            res++;
        }
    }
    cout << res << "\n";
}