#include <bits/stdc++.h>
using namespace std;
namespace fastinput {
inline int readChar();
template <class T = int>
inline T readInt();
template <class T>
inline void writeInt(T x, char end = 0);
inline void writeChar(int x);
inline void writeWord(const char *s);
static const int buf_size = 16384;
inline int getChar() {
  static char buf[buf_size];
  static int len = 0, pos = 0;
  if (pos == len) pos = 0, len = fread(buf, 1, buf_size, stdin);
  if (pos == len) return -1;
  return buf[pos++];
}
inline int readChar() {
  int c = getChar();
  while (c <= 32) c = getChar();
  return c;
}
template <class T>
inline T readInt() {
  int s = 1, c = readChar();
  T x = 0;
  if (c == '-') s = -1, c = getChar();
  while ('0' <= c && c <= '9') x = x * 10 + c - '0', c = getChar();
  return s == 1 ? x : -x;
}
static int write_pos = 0;
static char write_buf[buf_size];
inline void writeChar(int x) {
  if (write_pos == buf_size)
    fwrite(write_buf, 1, buf_size, stdout), write_pos = 0;
  write_buf[write_pos++] = (char)x;
}
template <class T>
inline void writeInt(T x, char end) {
  if (x < 0) writeChar('-'), x = -x;
  char s[24];
  int n = 0;
  while (x || !n) s[n++] = (char)('0' + x % 10), x /= 10;
  while (n--) writeChar(s[n]);
  if (end) writeChar(end);
}
inline void writeWord(const char *s) {
  while (*s) writeChar(*s++);
}
struct Flusher {
  ~Flusher() {
    if (write_pos) fwrite(write_buf, 1, write_pos, stdout), write_pos = 0;
  }
} flusher;
}  // namespace fastinput
using namespace fastinput;
vector<int> has1;
int main() {
  ::ios_base::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  int n = readInt(), m = readInt();
  for (int i = 0; i < m; ++i) {
    int k = readInt();
    set<int> v;
    for (int j = 0; j < k; ++j) {
      v.insert(readInt());
    }
    bool go = false;
    for (auto x : v)
      if (v.count(-x)) {
        go = true;
        break;
      }
    if (go == false) {
      puts("YES");
      return 0;
    }
  }
  puts("NO");
  return 0;
}
