#include using namespace std; using VI = vector; using VVI = vector; using PII = pair; using LL = long long; using VL = vector; using VVL = vector; using PLL = pair; using VS = vector; #define ALL(a) begin((a)),end((a)) #define RALL(a) (a).rbegin(), (a).rend() #define PB push_back #define EB emplace_back #define MP make_pair #define SZ(a) int((a).size()) #define SORT(c) sort(ALL((c))) #define RSORT(c) sort(RALL((c))) #define UNIQ(c) (c).erase(unique(ALL((c))), end((c))) #define FOR(i,a,b) for(int i=(a);i<(b);++i) #define REP(i,n) FOR(i,0,n) #define FF first #define SS second template istream& operator>>(istream& is, pair& p){ return is >> p.FF >> p.SS; } template ostream& operator<<(ostream& os, const pair& p){ return os << p.FF << " " << p.SS; } template void maxi(T& x, T y){ if(x < y) x = y; } template void mini(T& x, T y){ if(x > y) x = y; } const double EPS = 1e-10; const double PI = acos(-1.0); const LL MOD = 1e9+7; int main(){ cin.tie(0); ios_base::sync_with_stdio(false); int N, M; cin >> N >> M; vector> G(N); vector es(M); REP(i,M){ int a, b; cin >> a >> b; G[a].EB(b,i); G[b].EB(a,i); es[i] = MP(a, b); } vector vis(M); queue q; q.push(0); vis[0] = true; while(!q.empty()){ int i = q.front(); q.pop(); for(auto& e: G[es[i].FF]){ if(vis[e.SS]) continue; vis[e.SS] = true; q.push(e.SS); } for(auto& e: G[es[i].SS]){ if(vis[e.SS]) continue; vis[e.SS] = true; q.push(e.SS); } } int odd = 0; REP(i,N) odd += SZ(G[i]) % 2; if(count(ALL(vis), true) != M || odd > 2) cout << "NO" << endl; else cout << "YES" << endl; return 0; }