import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.NoSuchElementException;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		//FastScanner scanner=new FastScanner();
		PrintWriter out = new PrintWriter(System.out);
		int n=scanner.nextInt();
		int m=scanner.nextInt();
		int[] deg=new int[n];
		UnionFind uf=new UnionFind(n);
		for(int i=0; i<m; i++) {
			int sa=Integer.parseInt(scanner.next());
			int sb=Integer.parseInt(scanner.next());
			uf.unite(sa, sb);
			deg[sa]++;
			deg[sb]++;
		}
		int z=0;
		for(int i=0; i<n; i++) {
			if(deg[i]==0) {
				z++;
			}
		}
		if(uf.cmp-z>1) {
			out.println("NO");
			out.close();
			scanner.close();
			return;
		}
		int c=0;
		for(int i=0; i<n; i++) {
			if(deg[i]%2==1) c++;
		}
		if(c==0 || c==2) {
			out.println("YES");
		}else {
			out.println("NO");
		}
		out.close();
		scanner.close();
	}
}
class UnionFind{
	int n;
	int[] par;
	int cmp;
	public UnionFind(int n) {
		this.n=n;
		this.par=new int[n];
		Arrays.fill(this.par, -1);
		this.cmp=n;
	}
	public int find(int x) {
		if(par[x]<0) return x;
		return par[x]=find(par[x]);
	}
	public boolean unite(int x, int y) {
		x=find(x);
		y=find(y);
		if(x==y) {
			return false;
		}
		cmp--;
		if(par[x]>par[y]) {
			int tmp=x;
			x=y;
			y=tmp;
		}
		par[x]+=par[y];
		par[y]=x;
		return true;
	}
	public boolean same(int x, int y) {
		return find(x)==find(y);
	}
}
class FastScanner {
	private final InputStream in = System.in;
	private final byte[] buffer = new byte[1024];
	private int ptr = 0;
	private int buflen = 0;

	private boolean hasNextByte() {
		if (ptr < buflen) {
			return true;
		} else {
			ptr = 0;
			try {
				buflen = in.read(buffer);
			} catch (IOException e) {
				e.printStackTrace();
			}
			if (buflen <= 0) {
				return false;
			}
		}
		return true;
	}

	private int readByte() {
		if (hasNextByte())
			return buffer[ptr++];
		else
			return -1;
	}

	private static boolean isPrintableChar(int c) {
		return 33 <= c && c <= 126;
	}

	public boolean hasNext() {
		while (hasNextByte() && !isPrintableChar(buffer[ptr]))
			ptr++;
		return hasNextByte();
	}

	public String next() {
		if (!hasNext())
			throw new NoSuchElementException();
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while (isPrintableChar(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	public long nextLong() {
		if (!hasNext())
			throw new NoSuchElementException();
		long n = 0;
		boolean minus = false;
		int b = readByte();
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		if (b < '0' || '9' < b) {
			throw new NumberFormatException();
		}
		while (true) {
			if ('0' <= b && b <= '9') {
				n *= 10;
				n += b - '0';
			} else if (b == -1 || !isPrintableChar(b)) {
				return minus ? -n : n;
			} else {
				throw new NumberFormatException();
			}
			b = readByte();
		}
	}

	public int nextInt() {
		long nl = nextLong();
		if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
			throw new NumberFormatException();
		return (int) nl;
	}

	public double nextDouble() {
		return Double.parseDouble(next());
	}
}