NKONEARC

#include <bits/stdc++.h>
#define ll long long
using namespace std;

const int N = 2005;

int n, m;
vector<int> a[N];

int cnt, SCC, top;
int low[N], id[N], st[N], SCC_id[N], in[N], out[N];
bool visited[N];

void Tarjan(int u) {
    low[u] = id[u] = ++cnt;
    st[++top] = u;

    for(int v : a[u]) {
        if(visited[v]) continue;

        if(id[v] != 0)
            low[u] = min(low[u], id[v]);
        else {
            Tarjan(v);
            low[u] = min(low[u], low[v]);
        }
    }

    if(id[u] == low[u]) {
        SCC++;
        int v;
        while(v != u) {
            v = st[top--];
            SCC_id[v] = SCC;
            visited[v] = true;
        }
    }
}

int main()
{
    //freopen("in.txt", "r", stdin);
    //freopen("NKONEARC .inp", "r", stdin);
    //freopen("NKONEARC .out", "w", stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);

    cin >> n >> m;
    for(int i = 1; i <= m; i++) {
        int u, v;; cin >> u >> v;
        a[u].push_back(v);
    }

    for(int i = 1; i <= n; i++)
        if(id[i] == 0)
            Tarjan(i);

    for(int u = 1; u <= n; u++)
        for(int v : a[u]) {
            if(SCC_id[u] != SCC_id[v]) {
                ++in[SCC_id[v]];
                ++out[SCC_id[u]];
            }
        }

    int source = 0, sink = 0;
    int s = -1, t = -1;
    for(int i = 1; i <= SCC; i++) {
        if(in[i] == 0)
            source++, s = i;

        if(out[i] == 0)
            sink++, t = i;
    }

    if(source != 1 || sink != 1)
        cout << "NO" << '\n';
    else {
        cout << "YES" << '\n';

        for(int i = 1; i <= n; i++)
            if(SCC_id[i] == s) {
                s = i; break;
        }
        for(int i = 1; i <= n; i++)
            if(SCC_id[i] == t) {
                t = i; break;
        }
        cout << t << ' ' << s << '\n';
    }

    return 0;
}