Language: C++

#include<bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 1e9 + 7;
const int inf = (1 << 30) - 1;
const int64 infll = (1LL << 61) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename flow_t >
struct Dinic {
  const flow_t INF;

  struct edge {
    int to;
    flow_t cap;
    int rev;
    bool isrev;
  };

  vector< vector< edge > > graph;
  vector< int > min_cost, iter;

  Dinic(int V) : INF(numeric_limits< flow_t >::max()), graph(V) {}

  void add_edge(int from, int to, flow_t cap) {
    graph[from].emplace_back((edge) {to, cap, (int) graph[to].size(), false});
    graph[to].emplace_back((edge) {from, cap, (int) graph[from].size() - 1, true});
  }

  bool bfs(int s, int t) {
    min_cost.assign(graph.size(), -1);
    queue< int > que;
    min_cost[s] = 0;
    que.push(s);
    while(!que.empty() && min_cost[t] == -1) {
      int p = que.front();
      que.pop();
      for(auto &e : graph[p]) {
        if(e.cap > 0 && min_cost[e.to] == -1) {
          min_cost[e.to] = min_cost[p] + 1;
          que.push(e.to);
        }
      }
    }
    return min_cost[t] != -1;
  }

  flow_t dfs(int idx, const int t, flow_t flow) {
    if(idx == t) return flow;
    for(int &i = iter[idx]; i < graph[idx].size(); i++) {
      edge &e = graph[idx][i];
      if(e.cap > 0 && min_cost[idx] < min_cost[e.to]) {
        flow_t d = dfs(e.to, t, min(flow, e.cap));
        if(d > 0) {
          e.cap -= d;
          graph[e.to][e.rev].cap += d;
          return d;
        }
      }
    }
    return 0;
  }

  flow_t max_flow(int s, int t, int lim) {
    flow_t flow = 0;
    while(bfs(s, t)) {
      iter.assign(graph.size(), 0);
      flow_t f = 0;
      while((f = dfs(s, t, 5)) > 0) flow += f;
    }
    return flow;
  }

  void output() {
    for(int i = 0; i < graph.size(); i++) {
      for(auto &e : graph[i]) {
        if(e.isrev) continue;
        auto &rev_e = graph[e.to][e.rev];
        cout << i << "->" << e.to << " (flow: " << rev_e.cap << "/" << e.cap + rev_e.cap << ")" << endl;
      }
    }
  }
};


int main() {
  int N, M, X[100000], Y[100000];
  cin >> N >> M;
  int deg[100000] = {};
  for(int i = 0; i < M; i++) {
    cin >> X[i] >> Y[i];
    --X[i], --Y[i];
    deg[X[i]]++;
    deg[Y[i]]++;
  }
  vector< int > latte, malta;
  for(int i = 0; i < N; i++) {
    if(deg[i] & 1) {
      cout << "No" << endl;
      return 0;
    }
    if(deg[i] == 2) {
      latte.push_back(i);
    } else if(deg[i] == 4) {
      malta.push_back(i);
    }
  }

  if(latte.size() + malta.size() < N) {
    cout << "Yes" << endl;
    return 0;
  }

  if(malta.size() >= 3) {
    cout << "Yes" << endl;
    return 0;
  }

  if(malta.empty()) {
    cout << "No" << endl;
    return 0;
  }

  Dinic< int > flow(N);
  for(int i = 0; i < M; i++) flow.add_edge(X[i], Y[i], 1);
  if(flow.max_flow(malta[0], malta[1]) <= 2) {
    cout << "No" << endl;
    return 0;
  }

  cout << "Yes" << endl;
}





Compiler output:
a.cc: In function 'int main()':
a.cc:176:19: error: no matching function for call to 'Dinic<int>::max_flow(__gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type&, __gnu_cxx::__alloc_traits<std::allocator<int>, int>::value_type&)'
  176 |   if(flow.max_flow(malta[0], malta[1]) <= 2) {
      |      ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
a.cc:114:10: note: candidate: 'flow_t Dinic<flow_t>::max_flow(int, int, int) [with flow_t = int]'
  114 |   flow_t max_flow(int s, int t, int lim) {
      |          ^~~~~~~~
a.cc:114:10: note:   candidate expects 3 arguments, 2 provided