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

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int N, M, K;
    cin >> N >> M >> K;
    vector<vector<int>> g(N), gr(N);
    vector<pair<int,int>> edges;
    for(int i=0;i<M;i++){
        int u,v; cin >> u >> v; --u; --v;
        g[u].push_back(v);
        gr[v].push_back(u);
        edges.emplace_back(u,v);
    }

    vector<char> vis(N,false);
    stack<int> st;
    st.push(0);
    vis[0]=true;
    while(!st.empty()){
        int u=st.top(); st.pop();
        for(int v: g[u]) if(!vis[v]){
            vis[v]=true; st.push(v);
        }
    }
    for(int i=0;i<N;i++){
        if(!vis[i]){
            cout << "No" << endl;
            return 0;
        }
    }

    vector<char> ok(N,false);
    vector<int> X;
    function<void(int)> dfs1 = [&](int u){
        ok[u]=true;
        for(int v: g[u]) if(!ok[v]) dfs1(v);
        X.push_back(u);
    };
    for(int i=0;i<N;i++) if(!ok[i]) dfs1(i);

    vector<int> comp(N,-1);
    int val=0;
    function<void(int)> dfs2 = [&](int u){
        comp[u]=val;
        for(int v: gr[u]) if(comp[v]==-1) dfs2(v);
    };
    for(int i=N-1;i>=0;i--){
        int v = X[i];
        if(comp[v]==-1){
            dfs2(v);
            val++;
        }
    }

    vector<int> sz(val,0);
    vector<char> loop(val,false);
    for(int i=0;i<N;i++) sz[comp[i]]++;
    for(auto &e: edges){
        if(e.first==e.second) loop[comp[e.first]] = true;
    }

    int fir = comp[0];
    if(sz[fir]==1 && !loop[fir]){
        cout << "No" << endl;
        return 0;
    }

    cout << "Yes" << endl;
    return 0;
}