#ifdef DEBUG
  #define _GLIBCXX_DEBUG
  #define UNTIE ios_base::sync_with_stdio( false ); cin.tie( nullptr ); signal( SIGABRT , &AlertAbort )
  #define DEXPR( LL , BOUND , VALUE , DEBUG_VALUE ) CEXPR( LL , BOUND , DEBUG_VALUE )
  #define CERR( MESSAGE ) cerr << MESSAGE << endl;
  #define COUT( ANSWER ) cout << ANSWER << endl
  #define ASSERT( A , MIN , MAX ) CERR( "ASSERTチェック： " << ( MIN ) << ( ( MIN ) <= A ? "<=" : ">" ) << A << ( A <= ( MAX ) ? "<=" : ">" ) << ( MAX ) ); assert( ( MIN ) <= A && A <= ( MAX ) )
#else
  #pragma GCC optimize ( "O3" )
  #pragma GCC optimize( "unroll-loops" )
  #pragma GCC target ( "sse4.2,fma,avx2,popcnt,lzcnt,bmi2" )
  #define UNTIE ios_base::sync_with_stdio( false ); cin.tie( nullptr )
  #define DEXPR( LL , BOUND , VALUE , DEBUG_VALUE ) CEXPR( LL , BOUND , VALUE )
  #define CERR( MESSAGE ) 
  #define COUT( ANSWER ) cout << ANSWER << "\n"
  #define ASSERT( A , MIN , MAX ) assert( ( MIN ) <= A && A <= ( MAX ) )
#endif
#include <bits/stdc++.h>
using namespace std;
#define MAIN main
#define TYPE_OF( VAR ) decay_t<decltype( VAR )>
#define CEXPR( LL , BOUND , VALUE ) constexpr LL BOUND = VALUE
#define CIN( LL , A ) LL A; cin >> A
#define CIN_ASSERT( A , MIN , MAX ) TYPE_OF( MAX ) A; SET_ASSERT( A , MIN , MAX )
#define FOR( VAR , INITIAL , FINAL_PLUS_ONE ) for( TYPE_OF( FINAL_PLUS_ONE ) VAR = INITIAL ; VAR < FINAL_PLUS_ONE ; VAR ++ )
#define QUIT return 0
#define SET_ASSERT( A , MIN , MAX ) cin >> A; ASSERT( A , MIN , MAX )
#define RETURN( ANSWER ) COUT( ( ANSWER ) ); QUIT

#ifdef DEBUG
  inline void AlertAbort( int n ) { CERR( "abort関数が呼ばれました。assertマクロのメッセージが出力されていない場合はオーバーフローの有無を確認をしてください。" ); }
#endif

// 圧縮用
#define TE template
#define TY typename
#define US using
#define ST static
#define IN inline
#define CL class
#define PU public
#define OP operator
#define CE constexpr
#define CO const
#define NE noexcept
#define RE return 
#define WH while
#define VO void
#define VE vector
#define LI list
#define BE begin
#define EN end
#define SZ size
#define MO move
#define TH this
#define CRI CO int&
#define CRUI CO uint&
#define CRL CO ll&

// Tが加法について可換群をなす場合にのみサポート。

// - 構築 O(size)

// - 一点根取得 O(α(size))
// - 全根取得 O(size)
// - 根数取得 O(1)

// - 二点符号付き重み取得 O(α(size))
// - 二点接合 O(α(size))
template <typename T = int>
class UnionFindForest
{

private:
  uint m_node_size;
  uint m_root_size;
  vector<uint> m_pred;
  vector<uint> m_height;
  // m_w[num]はnum番目のnodeがrootならば0、rootでないならば親nodeへ向かうパスの符号付き重み
  vector<T> m_w;
  
public:
  inline UnionFindForest( const uint& size );

  // num番目のnodeのrootを計算して返す。
  const uint& RootOfNode( const uint& num );
  // rootを全て格納する。
  template <template <typename...> typename V> void SetRoot( V<uint>& a ) const;

  // num1番目のnodeからnum0番目のnodeへ向かうパスの符号付き重みを返す。
  inline T Weight( const uint& num0 , const uint& num1 );
  
  inline const uint& SizeOfNode() const noexcept;
  inline const uint& SizeOfRoot() const noexcept;

  // num1番目のnodeからnum0番目のnodeへ符号付き重みwの有向辺を結ぶ操作と整合的に
  // なるようにrootを接合。符号付き重みの整合性が取れない場合はfalseを返す。
  bool Graft( const uint& num0 , const uint& num1 , const T& w = 0 );
  
};

template <typename T> inline UnionFindForest<T>::UnionFindForest( const uint& size ) : m_node_size( size ) , m_root_size( m_node_size ) , m_pred( m_node_size ) , m_height( m_node_size , 1 ) , m_w( m_node_size ) { for( uint i = 0 ; i < m_node_size ; i++ ){ m_pred[i] = i; } }

template <typename T>
const uint& UnionFindForest<T>::RootOfNode( const uint& num )
{

  uint& pred1 = m_pred[num];

  while( true ){
    
    uint& pred2 = m_pred[pred1];

    if( pred1 == pred2 ){

      break;

    }

    m_w[num] += m_w[pred1] += m_w[pred2];
    pred1 = pred2 = m_pred[pred2];

  }

  return pred1;

}

template <typename T> template <template <typename...> typename V>
void UnionFindForest<T>::SetRoot( V<uint>& a ) const
{

  a.clear();

  for( uint i = 0 ; i < m_node_size ; i++ ){

    if( i == m_pred[i] ){
      
      a.push_back( i );

    }

  }

  return;

}

template <typename T>
T UnionFindForest<T>::Weight( const uint& num0 , const uint& num1 )
{

  assert( num0 < m_node_size && num1 < m_node_size );
  const uint& root0 = RootOfNode( num0 );
  const uint& root1 = RootOfNode( num1 );
  assert( root0 == root1 );
  return m_w[num1] - m_w[num0];

}

template <typename T> inline const uint& UnionFindForest<T>::SizeOfNode() const noexcept { return m_node_size; }
template <typename T> inline const uint& UnionFindForest<T>::SizeOfRoot() const noexcept { return m_root_size; }

template <typename T>
bool UnionFindForest<T>::Graft( const uint& num0 , const uint& num1 , const T& w )
{

  assert( num0 < m_node_size && num1 < m_node_size );
  const uint& root0 = RootOfNode( num0 );
  const uint& root1 = RootOfNode( num1 );

  if( root0 == root1 ){

    return Weight( num0 , num1 ) == w;
    
  }

  uint& height0 = m_height[root0];
  const uint& height1 = m_height[root1];
  const uint* p_removed_root;
  const uint* p_removed_node;
  const uint* p_kept_root;

  if( height0 < height1 ){

    p_removed_root = &root0;
    p_removed_node = &num0;
    p_kept_root = &root1;
    m_w[*p_removed_root] -= w - m_w[num1] + m_w[num0];

  } else {

    if( height0 == height1 ){

      height0++;

    }

    p_removed_root = &root1;
    p_removed_node = &num1;
    p_kept_root = &root0;
    m_w[*p_removed_root] += w - m_w[num1] + m_w[num0];

  }

  if( *p_removed_node != *p_removed_root ){

    m_w[*p_removed_node] += m_w[*p_removed_root];

  }
  
  m_pred[*p_removed_node] = m_pred[*p_removed_root] = *p_kept_root;
  m_root_size--;
  return true;

}

inline DEXPR( int , bound_N , 100000 , 100 ); // 0が5個
TYPE_OF( bound_N ) N;
inline DEXPR( int , bound_M , 100000 , 100 ); // 0が5個
TYPE_OF( bound_M ) M;

int MAIN()
{
  UNTIE;

  SET_ASSERT( N , 2 , bound_N );
  SET_ASSERT( M , 1 , bound_M );
  assert( M / ( N - 1 ) <= N );

  UnionFindForest<> uff{ N * 2 };
  string equiv[2] = { "<==>" , "<=/=>" };
  
  FOR( m , 0 , M ){
    CIN_ASSERT( i , 1 , N );
    CIN( string , E );
    CIN_ASSERT( j , i + 1 , N );
    i--;
    j--;
    int b = E == equiv[0] ? 0 : ( assert( E == equiv[1] ) , 1 );
    uff.Graft( i , j + b * N );
    uff.Graft( i + N , j + ( 1 - b ) * N );
  }

  int count_chosen = 0;
  int chosen_connected_component_num[bound_N*2] = {};
  FOR( i , 0 , N ){
    const int& connected_component_num_i = uff.RootOfNode( i );
    const int& connected_component_num_i_N = uff.RootOfNode( i + N );
    if( connected_component_num_i == connected_component_num_i_N ){
      RETURN( "No" );
    }
    int& chosen_connected_component_num_i = chosen_connected_component_num[connected_component_num_i];
    if( chosen_connected_component_num_i == 0 ){
      chosen_connected_component_num_i = 1;
      chosen_connected_component_num[connected_component_num_i_N] = 2;
    }
    if( chosen_connected_component_num_i == 1 ){
      count_chosen++;
    }
  }

  bool non_flip;
  if( count_chosen * 2 >= N ){
    non_flip = true;
  } else {
    non_flip = false;
    count_chosen = N - count_chosen;
  }
  COUT( "Yes" );
  COUT( count_chosen );

  FOR( i , 0 , N ){
    const int& connected_component_num_i = uff.RootOfNode( i );
    if( ( chosen_connected_component_num[connected_component_num_i] == 1 ) == non_flip ){
      cout << i + 1 << " \n"[--count_chosen==0];
    }
  }
  QUIT;
}