#include<bits/stdc++.h>
#include<atcoder/dsu>
using namespace atcoder;
using namespace std;

void dfs(int v,vector<vector<int>> &g,vector<bool> &seen) {
  seen[v]=true;
  for (auto v2:g[v]) {
    if (seen[v2]) continue;
    dfs(v2,g,seen);
  }
  return;
}

int main() {
  int n,m;
  cin>>n>>m;
  vector<vector<int>> g(2*n);
  dsu d(2*n);
  for (int i=0;i<m;i++) {
    string s;
    int a,b;
    cin>>a>>s>>b;
    a--;
    b--;
    if (s=="<==>") {
      g[a+n].push_back(b+n);
      g[b+n].push_back(a+n);
      g[a].push_back(b);
      g[b].push_back(a);
      d.merge(a,b);
      d.merge(a+n,b+n);
    }
    else {
      g[a+n].push_back(b);
      g[b].push_back(a+n);
      g[b+n].push_back(a);
      g[a].push_back(b+n);
      d.merge(a,b+n);
      d.merge(b,a+n);
    }
  }
  for (int i=0;i<n;i++) {
    if (d.same(i,i+n)) {
      cout<<"No"<<endl;
      return 0;
    }
  }
  
  vector<bool> seen(2*n,false);
  set<int> ans;
  
  for (int i=0;i<n;i++) {
    if (seen[i]) continue;
    queue<int> q;
    seen[i]=true;
    ans.insert(i);
    q.push(i);
    while(!q.empty()) {
      int v=q.front();
      q.pop();
      for (auto x:g[v]) {
        if (seen[x]) continue;
        if (x<n) {
          seen[x]=true;
          seen[x+n]=true;
        }
        else {
          seen[x]=true;
          seen[x-n]=true;
        }
        if (x<n) ans.insert(x);
        q.push(x);
      }
    }
  }
  cout<<"Yes"<<endl;
  
  cout<<ans.size()<<endl;
  cout<<*begin(ans)+1;
  ans.erase(*begin(ans));
  for (auto i:ans) cout<<" "<<i+1;
  cout<<endl;
}