#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  long long n, m, a, b;
  cin >> n >> m;
  for (long long i = 0; i < m; i++) {
    cin >> a;
    vector<long long> v(20005, 0);
    for (long long j = 0; j < a; j++) {
      cin >> b;
      if (b < 0)
        b = -b;
      else {
        b += 10000;
      }
      v[b] = 1;
    }
    bool flag1 = 0;
    for (long long j = 0; j < 10002; j++) {
      if (v[j] && v[j + 10000]) flag1 = 1;
    }
    if (flag1 == 0) {
      cout << "YES";
      return 0;
    }
  }
  cout << "NO";
  return 0;
}
