#include <bits/stdc++.h>
using namespace std;
int a[10010];
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  bool flag = false;
  for (int i = 1, k; i <= m; i++) {
    bool vis = false;
    scanf("%d", &k);
    for (int j = 1; j <= k; j++) scanf("%d", &a[j]);
    sort(a + 1, a + k + 1);
    int t = k;
    for (int j = 1; j <= k; j++) {
      while (a[j] + a[t] > 0 && t) t--;
      if (t <= 0) break;
      if (a[j] + a[t] == 0) vis = true;
    }
    if (!vis) flag = true;
  }
  if (flag)
    printf("YES\n");
  else
    printf("NO\n");
}
