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#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <set>
#include <map>
#include <utility>
#include <queue>
#include <vector>
#include <string>
#include <cstring>

#define REP(a,n) for (int a = 0; a<(n); ++a)
#define FOR(a,b,c) for (int a = (b); a<=(c); ++a)
#define FORD(a,b,c) for (int a = (b); a>=(c); --a)
#define FOREACH(a,v) for (auto a : v)

#define MP make_pair
#define PB push_back

template<class T> inline int size(const T&t) { return t.size(); }

using namespace std;

typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<string> vs;
typedef long long LL;

///////////////////////////////

int N, M;
int zm[1000001][3], op[3];

int main() {
  cin >> N >> M;
  REP(a, M) {
    int pocz, kon, kol;
    cin >> pocz >> kon >> kol;
    --kol;
    --pocz;
    zm[pocz][kol]++;
    zm[kon][kol]--;
  }
  int wyn = 0;
  REP(a, N) {
    REP(x, 3)
      op[x] += zm[a][x];
    if (op[0] && op[1] && !op[2])
      ++wyn;
  }
  cout << wyn << endl;
}