import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;



public class Main {
	
	public static void main(String[] args) throws IOException {
		Main m = new Main();
		//*
		m.input();
		m.solve();
		m.output();
		/*/
		m.debug();
		//*/
	}
	
	
	public void debug() {
	}
	InputUtil in = new InputUtil();
	PrintWriter out = new PrintWriter(System.out);
	
	int N,M;
	Range[] ranges;
	Map<Integer,List<Range>> rangeMap;
	List<Range> intersects;
	int ans = 0;
			
	public void input() throws IOException {
		N = in.nextInt();
		M = in.nextInt();
		ranges = new Range[M];
		rangeMap = new HashMap<>();
		intersects = new ArrayList<>();
		for (int i=0; i<M; i++) {
			ranges[i] = new Range(in.nextInt(),in.nextInt());
		}
		Arrays.sort(ranges);
	}

	public void solve() throws IOException {
		for (Range r: ranges) {
			boolean match = false;
			for (Range s : intersects) {
				if (s.applyIntersect(r)) {
					match=true;
					break;
				}
			}
			if(!match) {
				intersects.add(r);
			}
		}
	}
	
	public void output() {
		out.println(intersects.size());
		out.flush();
	}
	
}

class Range implements Comparable<Range> {
	public int a=0;
	public int b=0;
	public Range(int a, int b) {
		if (a>b) {
			set(b,a);
		}else{
			set(a,b);
		}
	}
	
	public Range clone() {
		return new Range(this.a,this.b);
	}

	public void set(int a, int b) {
		this.a=a;
		this.b=b;
	}
	public void set(Range r) {
		this.a=r.a;
		this.b=r.b;
	}

	public Range getIntersection(Range r) {
		if (r==null) return this;
		int aa = Math.max(a, r.a);
		int bb = Math.min(b, r.b);
		if (aa >= bb) {
			return null;
		}
		return new Range(aa,bb);
	}

	public boolean applyIntersect(Range r) {
		if (r==null) return false;
		int aa = Math.max(a, r.a);
		int bb = Math.min(b, r.b);
		if (aa < bb) {
			this.a=aa;
			this.b=bb;
			return true;
		}
		return false;
	}
	
	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + a;
		result = prime * result + b;
		return result;
	}
	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Range other = (Range) obj;
		if (a != other.a)
			return false;
		if (b != other.b)
			return false;
		return true;
	}

	@Override
	public int compareTo(Range r) {
		if (a==r.a) {
			return b-r.b;
		} else {
			return a-r.a;
		}
	}
	
	@Override
	public String toString() {
		return "("+a+","+b+")";
	}
	
}


class InputUtil {
	//Static Fields
	private static final int BUFSIZ = 100000;
	boolean lineMode = false;
	
	//Fields
	protected InputStream in;
	private byte[] buf = null;
	private int ptr = 0;
	private int max = -1;
	private DataInputStream dis = null;
	//Constructors
	public InputUtil() {this(System.in,BUFSIZ);}
	public InputUtil(InputStream in, int bufsiz) {
		initBuf(bufsiz);
		initIn(in);
	}
	
	//Methods
	//Initializer
	protected void initIn(InputStream in) {dis = new DataInputStream(this.in = in);}
	protected void initBuf(int bufsiz) {buf = new byte[bufsiz];}
	
	//buffer operation
	private void next() throws IOException {ptr++; readBuf();}
	private void readBuf() throws IOException {
		if(ptr >= max && dis.available()>0) {
			if(max>0) Arrays.fill(buf,0,max,(byte)0);
			max = dis.read(buf);
			ptr = 0;
		}
	}
	
	
	//String Input Reader/Parser
	private boolean isCrLf(byte b) {return b == 0x0a || b == 0x0d; }
	
	private void skipOneCrLf() throws IOException {
		byte b = buf[ptr];
		if (isCrLf(b)) {
			ptr++;
			if (b == 0x0d) {
				readBuf();
				if (ptr < max && buf[ptr] == 0x0a) {
					ptr++;
				}
			}
		}
	}
	
	public String nextLine() throws IOException {
		StringBuilder sb = new StringBuilder();
		boolean isFirst = true;
		for(readBuf(); ptr < max ;readBuf()) {
			byte b = buf[ptr];
			if(isCrLf(b)) {
				skipOneCrLf();
				if (!isFirst || lineMode) {
					break;
				}
			}else{
				int strPtr = ptr++;
				int endPtr = -1;
				for(int i = ptr; i<max; i++) {
					if(isCrLf(buf[i])) {
						endPtr = i;
						break;
					}
				}
				if(endPtr == -1) endPtr = max;
				sb.append(new String(buf,strPtr,endPtr-strPtr,"UTF-8"));
				ptr = endPtr;
			}
			isFirst = false;
		}
		lineMode = true;
		return sb.toString();
	}
	
	public byte nextByte() throws IOException {
		lineMode=false;
		readBuf();
		if(ptr < max) {
			return buf[ptr++];
		}else{
			return -1;
		}
	}
	
	//Number Input Reader/Parser
	private boolean isNum(byte b) {return '0' <= b && b <= '9'; }
	private boolean isMinus(byte b) {return b=='-'; }
	
	public int nextInt() throws IOException {
		lineMode=false;
		readBuf();
		return (int)_nextLong();
	}
	
	public int[] nextInt(int[] result) throws IOException {
		lineMode=false;
		readBuf();
		for(int i=0; i<result.length; i++) {
			result[i] = (int)_nextLong();
		}
		return result;
	}
	
	private long _nextLong() throws IOException {
		int sign = 1;
		long res = 0;
		byte c;
		while (!isNum(c=buf[ptr]) && !isMinus(c)) 
			next();
		if (isMinus(buf[ptr])) {
			sign = -1;
			next();
		}
		while (isNum(c=buf[ptr])) {
			res *= 10;
			res += c - '0' ;
			next();
		}
		next();
		return sign * res;
	}
	
	public long nextLong() throws IOException {
		lineMode=false;
		readBuf();
		return _nextLong();
	}
	
	public long[] nextLong(long[] result) throws IOException {
		lineMode=false;
		readBuf();
		for(int i=0; i<result.length; i++) {
			result[i] = _nextLong();
		}
		return result;
	}
	
	//Close 
	public void close() throws IOException {
		if(!this.in.equals(System.in)) 
			this.in.close();
	}

}

class OutputUtil {
	public static final String EOF = System.lineSeparator();

	public static void outputDivSpace(PrintWriter out, int[] a) {
		OutputUtil.output(out,a,0,a.length," ");
	}
	
	public static void outputDivEOF(PrintWriter out, int[] a) {
		OutputUtil.output(out,a,0,a.length,EOF);
	}
	
	public static void output(PrintWriter out, int[] a, int off, int len, String delim) {
		out.print(a[off]);
		for(int i=off+1; i<len; i++){
			out.print(delim);
			out.print(a[i]);
		}
		out.println("");
		out.flush();
	}
}


Measured memory_bytes: 30092