////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// [Tips]
// XCodeでのEOF入力はCtrl+D
// ¥はAlt+\
// ansは結構INTの範囲2,147,483,647を超えることがあるのでlong long使っておいたほうが良い
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////



////////////////////////////////////////
//
////////////////////////////////////////

//#define debug //*******************************************************************************************************************************************
#ifdef debug
#include <chrono>
#endif

#include <iostream>
#include <algorithm> // next_permutation
#include <iomanip>
#include <cmath>
#include <vector>
#include <sstream>
#include <string>
#include <cstring> //memcpy
#include <cstdio>
#include <stack>
#include <queue>
#include <list>
#include <numeric> //accumulate
//#include <map>
//#include <unordered_map> //hash func.
#include <fstream> //ifstream, ofstream
#include <iterator> //insert_iterator::inserter
#include <set>


//#define NDEBUG //If NDEBUG is defined before #include <cassert>, assert will be ignored. You had better define NDEBUG when u submit the code.
#include <cassert> //assert

using namespace std;


#define dout cout
//If u wanna output to a text file instead of standard output, plz define OUTPUTFILE.
//#define OUTPUTFILE "output.txt" //************************************************************
#ifdef OUTPUTFILE
#define dout outputfile
ofstream outputfile(OUTPUTFILE);
#define OutputFilePath "/Users/Nag/Documents/Prgm/Test/DerivedData/Test/Build/Products/Debug/output.txt"
#endif


#define din cin
//If u wanna input from a text file instead of standard input, plz define INPUTFROMTEXTFILEを.
//#define INPUTFILE "input.txt" //**************************************************************
#ifdef INPUTFILE
#define din inputfile
ifstream inputfile(INPUTFILE);
#endif

#define scand(A) scanf("%d", &(A))
#define scans(A) scanf("%s", (A))
#define printd(A) printf("%d\n", (A))
#define prints(A) printf("%s\n", (A))
#define disp(A) dout << #A << " = " << setw(3) << (A) << endl
#define disP(A) dout << setw(3) << (A) << " "
#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)
#define show(A,s,g) dout << #A << " = "; rep(j, (s), (g)) {disP(A[j]);} dout << endl
#define showi(A,s,g) dout << #A << " = "; rep(j, (s), (g)) {disP(j);} dout << endl


#define sign(x) ((x)>0)-((x)<0) //x<0: -1, x=0: 0, x>0: +1
#define p(i) ((i)/2)
#define l(i) ((i)*2)
#define r(i) ((i)*2+1)
#define sibling(i) (i^1) //the other sibling of i (ex. 16^1 = 17, 17^1 = 16)
#define isRightChild(i) (i&1) // ex. 16&1 = 0, 17&1 = 1
#define isLeftChild(i) (!(i&1)) // ex. 16&1 = 1, 17&1 = 0

int dx[] = {1, 0, -1,  0};
int dy[] = {0, 1,  0, -1};

typedef pair<int,int> ii;
typedef pair<ii, int> iii;
typedef vector<int> vi;
typedef long long ll;
typedef unsigned long long ull;

const int INF = (1LL<<31)-1;
const ll INF_LL = (ll)9e18-1LL; //Be careful for overflow.
const ull INF_ULL = (ull)1e19-1ULL;
const int NONE = -1;
//const ll MOD = (ll)1e9+7; //大きい素数の代表といえばこの人、10億7さん
const int MOD = 16411;

const int N_MAX = 510; //num of vertex or element
const int M_MAX = 124760; //num of edge
const int DATA_MAX = 1010;

int N, M;
int root[N_MAX];
int degree[N_MAX];

ii e[M_MAX];

int ans = 0;


void init() {
    rep(i,0,N) {
        root[i] = i;
        degree[i] = 0;
    }
}


int find(int x) {
    if(root[x]==x) return x;
    else return root[x] = find(root[x]);
}

void unite(int x, int y) {
    x = find(x);
    y = find(y);
    
    root[x] = y;
}


bool checkIfOddDegreeAre0or2() {
#ifdef debug
    dout << "--- checkIfOddDegreeAre0or2()\n";
#endif
    
    int numOfOddDegree = 0;
    
    rep(i,0,N) {
        if(degree[i]%2) {
            numOfOddDegree++;
        }
        
#ifdef debug
        dout << "--\n";
        disp(i);
        disp(degree[i]);
        disp(numOfOddDegree);
#endif
        
    }
    
    
    if(numOfOddDegree==0 or numOfOddDegree==2) return true;
    else return false;
    
}





bool checkIfAllEdgesAreConnected() {

    bool ret = true;

    int r = find(e[0].first);
#ifdef debug
    dout << "--- checkIfAllEdgesAreConnected()\n";
    disp(e[0].first);
    disp(e[0].second);
    disp(r);
#endif
    
    rep(i,1,M) {
        if(r != find(e[i].first)) ret = false;

#ifdef debug
        dout << "--\n";
        disp(e[i].first);
        disp(find(e[i].first));
        disp(e[i].second);
        disp(find(e[i].second));
        disp(ret);
#endif
    }
    
    return ret;
}


void display() {
#ifdef debug
    dout << "----\n";
    
    dout << "     "; showi(i, 0, N);
    dout << "  "; show(root,0,N);
    
    show(degree,0,N);
    
#endif
}



int main() {
    
    //cin, coutの高速化  ＊注意：cinを使うなら全部cinで、scanfを使うなら全部scanfで統一するように！
    cin.tie(0); //cinとcoutの同期を切る
    ios::sync_with_stdio(false); //iostreamとstdioの同期を切る
    
    //read input data
//    scand(N);
    
    din >> N >> M;
    
    init();
    display();

    int s, g;
    rep(i,0,M) {
        din >> s >> g;
        
        degree[s]++;
        degree[g]++;
        unite(s, g);
        e[i] = make_pair(s, g);
    }
    
    
    display();

    
    
    //------------------------------------------------------------------------------------------
#ifdef debug
    //start timer
    auto startTime = chrono::system_clock::now();
#endif
    //------------------------------------------------------------------------------------------
    
    
    
    
    
    
#ifdef debug
    dout << "=== OUTPUT ===\n";
#endif
    if(checkIfAllEdgesAreConnected() and checkIfOddDegreeAre0or2()) dout << "YES" << endl;
    else dout << "NO" << endl;
    
    
    
    
    
    
    //------------------------------------------------------------------------------------------
#ifdef debug
    //stop timer
    auto endTime = chrono::system_clock::now();
    auto dur = endTime - startTime;
    auto msec = chrono::duration_cast<chrono::milliseconds>(dur).count();
    dout << fixed << setprecision(4) << (double)msec/1000 << " sec \n";
#endif
    //------------------------------------------------------------------------------------------
    
#ifdef INPUTFILE
    inputfile.close();
#endif
    
#ifdef OUTPUTFILE
    outputfile.close();
    cout << "\"" << OutputFilePath << "\"" << endl;
#endif
    
    return 0;
}