1682.cpp

#include <bits/stdc++.h>

using namespace std;

#define print_op(...) ostream& operator<<(ostream& out, const __VA_ARGS__& u)
template<typename A, typename B> print_op(pair<A, B>) { return out << "(" << u.first << ", " << u.second << ")"; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> print_op(T_container) { out << "{"; string sep; for (const T &x : u) out << sep << x, sep = ", "; return out << "}"; }
template<typename T> void dbg_out(string s, T x) {cerr << "\033[1;35m" << s << "\033[0;32m = \033[33m" << x << "\033[0m\n";}
template<typename T, typename... Args> void dbg_out(string s, T x, Args... args) {for (int i=0, b=0; i<(int)s.size(); i++) if (s[i] == '(' || s[i] == '{') b++; else
if (s[i] == ')' || s[i] == '}') b--; else if (s[i] == ',' && b == 0) {cerr << "\033[1;35m" << s.substr(0, i) << "\033[0;32m = \033[33m" << x << "\033[31m | "; dbg_out(s.substr(s.find_first_not_of(' ', i + 1)), args...); break;}}
#ifdef LOCAL
#define dbg(...) dbg_out(#__VA_ARGS__, __VA_ARGS__)
#else
#define dbg(...)
#endif

#define ar array
#define ll long long
#define ld long double
#define sz(x) ((int)x.size())
#define rep(i, a, b) for (int i = (int)(a); i < (int)(b); i++) 
#define all(a) (a).begin(), (a).end()

const int MAX_N = 1e5 + 5;
const int MAX_L = 20;
const int MAX_C = 26;
const ll MOD = 1e9 + 7;
const ll INF = 1e9;
const ld EPS = 1e-9;

struct SCC {
    int n, ti;
    vector<int> num, id, stk;
    vector<vector<int>> adj, dag, comp;
 
    SCC(int _n) : n(_n), ti(0), num(n), id(n, -1), adj(n) {}
 
    void addEdge(int u, int v) {
        adj[u].push_back(v);
    }
    
    void init() {
        for (int u = 0; u < n; u++)
            if (!num[u])
                dfs(u);
        dag.resize(comp.size());
        for (auto &c : comp)
            for (int u : c)
                for (int v : adj[u])
                    if (id[u] != id[v])
                        dag[id[u]].push_back(id[v]);
        for (auto &v : dag) {
            sort(v.begin(), v.end());
            v.erase(unique(v.begin(), v.end()), v.end());
        }
    }
 
    int dfs(int u) {
        int low = num[u] = ++ti;
        stk.push_back(u);
        for (int v : adj[u]) {
            if (!num[v])
                low = min(low, dfs(v));
            else if (id[v] == -1)
                low = min(low, num[v]);
        }
        if (low == num[u]) {
            comp.emplace_back();
            do {
                id[stk.back()] = (int) comp.size() - 1;
                comp.back().push_back(stk.back());
                stk.pop_back();
            } while (comp.back().back() != u);
        }
        return low;
    }
};
 
void solve(int tc = 0) {
    int n, m; cin >> n >> m;
    SCC scc(n);
    while (m--) {
        int u, v; cin >> u >> v; u--; v--;
        scc.addEdge(u, v);
    }
    scc.init();
    if (sz(scc.comp) == 1) {
        cout << "YES\n";
    } else {
        cout << "NO\n" << scc.comp[0][0] + 1 << " " << scc.comp[1][0] + 1 << "\n";
    }
}

signed main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    int tc = 1;
    // cin >> tc;
    for (int t = 1; t <= tc; t++) {
        // cout << "Case #" << t << ": ";
        solve(t);
    }
}