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

#define VA_NUM_ARGS(...) VA_NUM_ARGS_IMPL_((0,__VA_ARGS__, 6,5,4,3,2,1))
#define VA_NUM_ARGS_IMPL_(tuple) VA_NUM_ARGS_IMPL tuple
#define VA_NUM_ARGS_IMPL(_0,_1,_2,_3,_4,_5,_6,N,...) N
#define macro_dispatcher(macro, ...) macro_dispatcher_(macro, VA_NUM_ARGS(__VA_ARGS__))
#define macro_dispatcher_(macro, nargs) macro_dispatcher__(macro, nargs)
#define macro_dispatcher__(macro, nargs) macro_dispatcher___(macro, nargs)
#define macro_dispatcher___(macro, nargs) macro ## nargs
#define Debug1(a)           cout<<#a<<"="<<(a)<<"\n"
#define Debug2(a,b)         cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<"\n"
#define Debug3(a,b,c)       cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<"\n"
#define Debug4(a,b,c,d)     cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<"\n"
#define Debug5(a,b,c,d,e)   cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<", "<<#e<<"="<<(e)<<"\n"
#define Debug6(a,b,c,d,e,f) cout<<#a<<"="<<(a)<<", "<<#b<<"="<<(b)<<", "<<#c<<"="<<(c)<<", "<<#d<<"="<<(d)<<", "<<#e<<"="<<(e)<<", "<<#f<<"="<<(f)<<"\n"
#define Debug(...) macro_dispatcher(Debug, __VA_ARGS__)(__VA_ARGS__)
#define DA(a,n) cout<<#a<<"=["; printarray(a,n); cout<<"]\n"
#define DAR(a,n,s) cout<<#a<<"["<<s<<"-"<<n-1<<"]=["; printarray(a,n,s); cout<<"]\n"

#define TT1 template<class T>
#define TT1T2 template<class T1, class T2>
#define TT1T2T3 template<class T1, class T2, class T3>
template<class T, size_t N> ostream& operator << (ostream& os, const array<T, N>& v);
TT1T2 ostream& operator << (ostream& os, const pair<T1, T2>& p){ return os <<"("<<p.first<<", "<< p.second<<")"; }
TT1 ostream& operator << (ostream& os, const vector<T>& v){       bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
template<class T, size_t N> ostream& operator << (ostream& os, const array<T, N>& v) {     bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
TT1T2 ostream& operator << (ostream& os, const set<T1, T2>&v){    bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
TT1T2 ostream& operator << (ostream& os, const multiset<T1,T2>&v){bool f=1;os<<"[";for(auto& i : v) { if (!f)os << ", ";os<<i;f=0;}return os << "]"; }
TT1T2T3 ostream& operator << (ostream& os, const map<T1,T2,T3>& v){ bool f = 1; os << "["; for (auto& ii : v) { if (!f)os << ", "; os << "(" << ii.first << " -> " << ii.second << ") "; f = 0; }return os << "]"; }
TT1T2 ostream& operator << (ostream& os, const multimap<T1, T2>& v){ bool f = 1; os << "["; for (auto& ii : v) { if (!f)os << ", "; os << "(" << ii.first << " -> " << ii.second << ") "; f = 0; }return os << "]"; }
TT1T2 ostream& operator << (ostream& os, priority_queue<T1, T2> v) { bool f = 1; os << "["; while (!v.empty()) { auto x = v.top(); v.pop(); if (!f) os << ", "; f = 0; os << x; } return os << "]"; }
TT1T2 void printarray(const T1& a, T2 sz, T2 beg = 0){ for (T2 i = beg; i<sz; i++) cout << a[i] << " "; cout << endl; }


#define geti1(X) cin >> X
#define geti2(X,Y) cin >> X >> Y
#define geti3(X,Y,Z) cin >> X >> Y >> Z
#define geti4(X,Y,Z,W) cin >> X >> Y >> Z >> W
#define GET_MACRO(_1,_2,_3,_4,NAME,...) NAME
#define geti(...) GET_MACRO(__VA_ARGS__, geti4, geti3, geti2, geti1) (__VA_ARGS__)

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

#define Fi first
#define Se second
#define pb(x) push_back(x)
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define rep(i,n) for(int i=0;i<n;i++)
#define repp(i,n) for(int i=1;i<=n;i++)

#define endl '\n'

int N,M;
multiset<int> S[100500];
int main() {
	ios::sync_with_stdio(false); cin.tie(NULL);
	geti(N,M);
	queue<pii> q;
	repp(i,M){
		int a,b; geti(a,b);
		S[a].insert(b); S[b].insert(a);
		q.push({a,b});
	}
	while( !q.empty() ){
		int a = q.front().Fi, b = q.front().Se; q.pop();
		
		if( S[a].count(b) == 0 || S[b].count(a) == 0 ) continue;
		if( S[a].count(b) >= 2 && S[b].count(a) >= 2 ){
			auto it = S[a].find(b); S[a].erase(it);
			it = S[a].find(b); S[a].erase(it);
			it = S[b].find(a); S[b].erase(it);
			it = S[b].find(a); S[b].erase(it);
			continue;
		}

		if( sz(S[a]) >= 2 ){
			for(auto it = S[a].begin(); it != S[a].end(); it++) {
				
				if( (*it) != b ){
					int c = *it;
					S[a].erase(it);
					auto it1 = S[c].find(a); S[c].erase(it1);
					auto it2 = S[a].find(b); S[a].erase(it2);
					auto it3 = S[b].find(a); S[b].erase(it3);
					S[b].insert(c); S[c].insert(b);
					q.push({b,c});
					
					break;
				}
			}
			continue;
		}

		if( sz(S[b]) >= 2 ){
			for(auto it = S[b].begin(); it != S[b].end(); it++) {
				if( *it != a ){
					int c = *it;
					S[b].erase(it);
					auto it1 = S[c].find(b); S[c].erase(b);
					auto it2 = S[b].find(a); S[b].erase(it2);
					it2 = S[a].find(b); S[a].erase(it2);
					S[a].insert(c); S[c].insert(a);
					q.push({a,c});
					
					break;
				}
			}
			continue;
		}

	}

	repp(i,N){
		if( sz(S[i]) >= 1 ){
			cout << "NO\n"; return 0;
		}
	}
	cout << "YES\n";

}



Measured memory_bytes: 15232