#include "bits/stdc++.h"
#define REP(i,n,N) for(int i=(n); i<(N); i++)
#define RREP(i,n,N) for(ll i=(N-1); i>=n; i--)
#define CK(n,a,b) ((a)<=(n)&&(n)<(b))
#define ALL(v) (v).begin(),(v).end()
#define p(s) cout<<(s)<<endl
#define p2(a,b) cout<<(a)<<" "<<(b)<<endl
#define v2(T) vector<vector<T>>
typedef long long ll;
using namespace std;
const ll inf = 1e18+7;

int num[510];
int main(){
    int N,M;
    cin>>N>>M;
    REP(i,0,M){
        int a,b;
        cin>>a>>b;
        a--;b--;
        num[a]++;
        num[b]++;
    }
    int cnt=0;
    REP(i,1,N){
        if(num[i]%2){
            cnt++;
        }
    }
    p(cnt<=1?"YES":"NO");
    return 0;
}