#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define rep1(i, n) for (int i = 1; i <= (n); i++)
#define rrep(i, n) for (int i = n - 1; i >= 0; i--)
#define rrep1(i, n) for (int i = n; i >= 1; i--)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define eb emplace_back
#define fi first
#define se second
#define sz(x) (int)(x).size()
template <class T> using V = vector<T>;
template <class T> using VV = V<V<T>>;
typedef long long int ll;

void speedUpIO() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
}

template <class T> bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template <class T> bool chmin(T &a, const T &b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}
/*--------------------------------------------------*/
typedef pair<int, int> P;
typedef pair<P, int> PP;

const int INF = 1e9;
const ll LINF = 1e18;
const int MX = 100010;

void solve() {
    int n, m;
    cin >> n >> m;
    VV<int> G(n);
    set<PP> st;
    rep(mi, m) {
        int i, j;
        string e;
        cin >> i >> e >> j;
        i--, j--;
        int ei = 0;
        if (e == "<==>") ei = 1;
        st.insert({{i, j}, ei});
        st.insert({{j, i}, ei});
        G[i].eb(j);
        G[j].eb(i);
    }
    V<int> col(n, -1);
    bool ans = true;
    auto dfs = [&](auto dfs, int u, V<int> &a) -> void {
        for (auto v : G[u]) {
            if (col[v] == -1) {
                if (st.count({{u, v}, 0})) {
                    col[v] = 1 - col[u];
                } else if (st.count({{u, v}, 1})) {
                    col[v] = col[u];
                } else {
                    assert(false);
                }
                a.eb(v);
                dfs(dfs, v, a);
            } else {
                if (st.count({{u, v}, 0})) {
                    if (col[u] == col[v]) {
                        ans = false;
                        return;
                    }
                }
                if (st.count({{u, v}, 1})) {
                    if (col[u] != col[v]) {
                        ans = false;
                        return;
                    }
                }
            }
        }
    };
    V<int> b;
    rep(i, n) {
        if (col[i] == -1) {
            col[i] = 0;
            V<int> a = {i};
            dfs(dfs, i, a);
            if (!ans) break;
            int cnt = 0;
            for (auto v : a) {
                if (col[v] == 1) cnt++;
            }
            for (auto v : a) {
                int c = cnt >= (n + 1) / 2 ? 1 : 0;
                if (col[v] == c) b.eb(v);
            }
        }
    }
    if (!ans) {
        cout << "No\n";
        return;
    }
    cout << "Yes\n";
    cout << sz(b) << "\n";
    sort(all(b));
    for (auto v : b) {
        cout << v + 1 << " ";
    }
    cout << "\n";
}

int main() {
    speedUpIO();
    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
        // cout << solve() << "\n";
        // cout << (solve() ? "YES" : "NO") << "\n";
        // cout << fixed << setprecision(15) << solve() << "\n";
    }
    return 0;
}