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#include <cstdio>
using namespace std;

const int MX = 1e6;
const int C = 3;

int n, m, r, add[MX+1][C+1], sub[MX+1][C+1], now[C+1];


int main() {
  scanf("%d%d", &n, &m);
  while (m--) {
    int a, b, c;
    scanf("%d%d%d", &a, &b, &c);
    ++add[a][c];
    ++sub[b][c];
  }
  for (int i = 1; i <= n; ++i) {
    for (int c = 1; c <= C; ++c) now[c] += add[i][c];
    if (now[1] && now[2] && !now[3]) ++r;
    for (int c = 1; c <= C; ++c) now[c] -= sub[i][c];
  }
  printf("%d\n", r);
  return 0;
}