#include <bits/stdc++.h>
using namespace std;
const int N = 1e5, M = 2e4;
int vis[N + 4];
int main() {
  int n, m, flag, ff = 0;
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= m; i++) {
    int x, a;
    flag = 1;
    memset(vis, 0, sizeof(vis));
    scanf("%d", &x);
    for (int j = 1; j <= x; j++) {
      scanf("%d", &a);
      if (a > 0) {
        if (vis[M - a] == 1) {
          flag = 0;
        }
      } else {
        if (vis[M - a] == 1) {
          flag = 0;
        }
      }
      vis[M + a] = 1;
    }
    if (flag == 1) {
      ff = 1;
    }
  }
  if (ff == 1) {
    printf("YES\n");
  } else
    printf("NO\n");
}
