#include <iostream>
#include <vector>

using namespace std;

int main(){

    int station;
    int strain;
    int start, end;
    vector<int> stationflag;
    int odd=0;
    int even=0;

    cin>>station>>strain;
    stationflag.resize(station);

    for(int i=0; i<strain; ++i)
    {
        cin>>start>>end;
        stationflag[start]++;
        stationflag[end]++;
    }

    for(int i=0; i<station; ++i)
    {
        if(stationflag[i] % 2 == 0)
            even++;
        else
            odd++;
    }

    if(station%2==0)
    {
        if(odd==2 || odd == 0)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
    }
    else
    {
        if(odd==2)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
    }


    return 0;
}