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

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
#define rep3(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define rep2(i, a, b) rep3(i, a, b, 1)
#define rep1(i, n) rep2(i, 0, n)
#define rep0(n) rep1(aaaaa, n)
#define ov4(a, b, c, d, name, ...) name
#define rep(...) ov4(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__)
#define per(i, a, b) for (ll i = (a) - 1; i >= (b); i--)
#define fore(e, v) for (auto &&e : v)
#define all(a) begin(a), end(a)
#define sz(a) (ssize(a))
#define lb(v, x) (lower_bound(all(v), x) - begin(v))
#define eb emplace_back

template <typename T, typename S> bool chmin(T &a, const S &b) {
  return a > b ? a = b, 1 : 0;
}
template <typename T, typename S> bool chmax(T &a, const S &b) {
  return a < b ? a = b, 1 : 0;
}
const int INF = 1e9 + 100;
const ll INFL = 3e18 + 100;
#define i128 __int128_t
struct _ {
  _() { cin.tie(0)->sync_with_stdio(0), cout.tie(0); }
} __;

template <typename G> struct SCC {
  G g; // vector<vi> or vector<vl>
  vector<vi> rg;
  vi comp, ord, used;
  int num; // 連結成分の数
  SCC(G g) : g(g), rg(sz(g)), comp(sz(g), -1), ord(sz(g)), used(sz(g)) {
    rep(i, sz(g)) fore(e, g[i]) rg[e].eb(i);
    build();
  }; // 4587f363
  int operator[](int k) { return comp[k]; }
  void dfs(int x) {
    if (used[x])
      return;
    used[x] = true;
    fore(e, g[x]) if (!used[e]) dfs(e);
    ord.eb(x);
  } // 14b1a925
  void rdfs(int x, int cnt) {
    if (comp[x] != -1)
      return;
    comp[x] = cnt;
    fore(e, rg[x]) if (comp[e] == -1) rdfs(e, cnt);
  } // de35b0e0
  void build() {
    rep(i, g.size()) dfs(i);
    reverse(all(ord));
    num = 0;
    fore(i, ord) if (comp[i] == -1) { rdfs(i, num), num++; }
  } // d3ed3d5a
};

int main() {
  int N, M, K;
  cin >> N >> M >> K;
  vector<vi> G(N);
  rep(M) {
    int U, V;
    cin >> U >> V;
    --U, --V;
    G[U].push_back(V);
  }
  SCC s(G);
  s.build();
  vi cnt(N);
  fore(i, s.comp) cnt[i]++;
  vi dist(N, INF);
  bool ok = 1;
  rep(i, N) {
    if (dist[i] != INF)
      continue;
    queue<int> bfs;
    dist[i] = 0;
    bfs.push(i);
    bool bi = cnt[s.comp[i]] > 1;
    while (!bfs.empty()) {
      int v = bfs.front();
      bfs.pop();
      for (auto u : G[v]) {
        if (s.comp[u] == s.comp[i] && dist[u] > dist[v] + 1) {
          dist[u] = dist[v] + 1;
          bfs.push(u);
        }
        if (s.comp[u] == s.comp[i] && dist[u] % 2 == dist[v] % 2)
          bi = 0;
      }
    }
    if (bi)
      ok = 0;
  }

  if (s.comp[0] != 0)
    ok = 0;
  if (cnt[s.comp[0]] == 1)
    ok = 0;
  rep(i, N) {
    if (cnt[i] == 1 && cnt[i + 1] == 1)
      ok = 0;
  }

  cout << (ok ? "Yes\n" : "No\n");
}