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#include <bits/stdc++.h>
using namespace std;

typedef long long LL;
typedef long double LD;
typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;

#define all(x) (x).begin(), (x).end()
#define sz(x) (int)(x).size()

template<typename _T> inline void _DBG(const char *s, _T x) { cerr << s << " = " << x << "\n"; }
template<typename _T, typename... args> void _DBG(const char *s, _T x, args... a) { while(*s != ',') cerr << *s++; cerr << " = " << x << ','; _DBG(s + 1, a...); }

#ifdef LOCAL
#define _upgrade ios_base::sync_with_stdio(0);
#define DBG(...) _DBG(#__VA_ARGS__, __VA_ARGS__)
#else
#define _upgrade ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define DBG(...) (__VA_ARGS__)
#define cerr if(0) cout
#endif

// ********************** CODE ********************** //

const int N = 1e6 + 7;

int n, m, T[3][N];

int main()
{
    _upgrade
    
    cin >> n >> m;
    for(int i = 0; i < m; i++)
    {
        int l, r, k;
        cin >> l >> r >> k;
        k--;
        T[k][l]++;
        T[k][r + 1]--;
    }

    for(int i = 0; i < 3; i++)
    {
        for(int j = 1; j <= n; j++)
        {
            T[i][j] += T[i][j - 1];
        }
    }

    int ans = 0;
    for(int i = 1; i <= n; i++)
    {
        if(T[0][i] > 0 && T[1][i] > 0 && T[2][i] == 0)
            ans++;
    }

    cout << ans << "\n";

    return 0;
}