#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic warning "-Wunused-function"
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m, k;
  cin >> n >> m >> k;
  scc_graph g(n);
  VVI to(n);
  rep(_, m) {
    int u, v;
    cin >> u >> v;
    u--, v--;
    g.add_edge(u, v);
    to[u].emplace_back(v);
  }
  auto scc = g.scc();
  VI cls(n);
  rep(i, ssize(scc)) for (int v : scc[i]) cls[v] = i;
  bool ans = cls[0] == 0 && ssize(scc[0]) >= 2;
  rep(i, ssize(scc) - 1) {
    bool ok = false;
    for (int u : scc[i]) for (int v : to[u]) if (cls[v] == i + 1) ok = true;
    ans &= ok;
    ans &= ssize(scc[i]) != 1 || ssize(scc[i+1]) != 1;
  }
  dsu uf(2 * n);
  rep(i, ssize(scc)) if (scc[i].size() >= 2) {
    for (int u : scc[i]) for (int v : to[u]) if (cls[v] == i) {
      uf.merge(u, n + v);
      uf.merge(v, n + u);
    }
    ans &= uf.same(scc[i][0], scc[i][0] + n);
  }
  cout << (ans ? "Yes\n" : "No\n");
}