You are given n segments on the Ox-axis. You can drive a nail in any integer point on the Ox-axis line nail so, that all segments containing this point, are considered nailed down. If the nail passes through endpoint of some segment, this segment is considered to be nailed too. What is the smallest number of nails needed to nail all the segments down?

Input

The first line of the input contains single integer number n (1 ≤ n ≤ 1000) — amount of segments. Following n lines contain descriptions of the segments. Each description is a pair of integer numbers — endpoints coordinates. All the coordinates don't exceed 10000 by absolute value. Segments can degenarate to points.

Output

The first line should contain one integer number — the smallest number of nails needed to nail all the segments down. The second line should contain coordinates of driven nails separated by space in any order. If the answer is not unique, output any.

Examples

Input

2
0 2
2 5


Output

1
2 

Input

5
0 3
4 2
4 8
8 10
7 7


Output

3
7 10 3

        		    import java.awt.Checkbox;
import java.awt.Point;
import java.io.*;
        		    import java.math.*;
        		    import java.util.*;
        		    import javax.print.attribute.SetOfIntegerSyntax;
     
     
     
        		    public class LIS{
        		    	private static InputStream stream;
        		    	private static byte[] buf = new byte[1024];
        		    	private static int curChar;
        		    	private static int numChars;
        		    	private static SpaceCharFilter filter;
        		    	private static PrintWriter pw;
        		    	private static long count = 0,mod=1000000007;
        		    //	private static TreeSet<Integer> ts=new TreeSet[200000];
 
    		        public static void main(String[] args) {
    		        	InputReader(System.in);
    		    		pw = new PrintWriter(System.out); 
    		            new Thread(null ,new Runnable(){
    		               public void run(){
    		                   try{
    		                       solve();
    		                       pw.close();
    		                   } catch(Exception e){
    		                       e.printStackTrace();
    		                   }
    		               }
    		           },"1",1<<26).start();
   }
    public static void Merge(long a[],int p,int r){
        if(p<r){
            int q = (p+r)/2;
            Merge(a,p,q);
            Merge(a,q+1,r);
            Merge_Array(a,p,q,r);
        }
    }
    public static void Merge_Array(long a[],int p,int q,int r){
       long b[] = new long[q-p+1];
        long c[] = new long[r-q];
        for(int i=0;i<b.length;i++)
            b[i] = a[p+i];
        for(int i=0;i<c.length;i++)
            c[i] = a[q+i+1];
        int i = 0,j = 0;
        for(int k=p;k<=r;k++){
            if(i==b.length){
                a[k] = c[j];
                j++;
            }
            else if(j==c.length){
                a[k] = b[i];
                i++;
            }
            else if(b[i]<c[j]){
                a[k] = b[i];
                i++;
            }
            else{
                a[k] = c[j];
                j++;
            }
        }
    }
	public static long gcd(long x, long y) {
		if (x == 0)
			return y;
		else
			return gcd( y % x,x);
	}	public static boolean isPrime(int n) {
	// Corner cases
		if (n <= 1)
			return false;
		if (n <= 3)
			return true;
 
		// This is checked so that we can skip 
// middle five numbers in below loop
		if (n % 2 == 0 || n % 3 == 0)
			return false;
 
		for (int i = 5; i * i <= n; i = i + 6)
			if (n % i == 0 || n % (i + 2) == 0)
				return false;
 
		return true;
	}
      
        public static void solve() {
  
 
        	int n=nextInt();
        	Pair p[]=new Pair[n];
        	for(int i=0;i<n;i++){
        		int x=nextInt();
        		int y=nextInt();
        		p[i]=new Pair(Math.min(x, y),Math.max(x, y));
        	}
        	
        	Arrays.sort(p);
        	int cnt=0;
        	int curr_s=p[0].start;
        	int curr_e=p[0].end;
        	ArrayList<Integer> ans=new ArrayList<Integer>();
        	
        	for(int i=1;i<n;i++){
        	
        		if(p[i].start>curr_e){
        			ans.add(curr_e);
        			curr_s=p[i].start;
        			curr_e=p[i].end;
        		}else{
        			curr_e=Math.min(curr_e, p[i].end);
        		}
        		
        	}
        	ans.add(curr_e);
        	pw.println(ans.size());
        	for(int i=0;i<ans.size();i++){
        		pw.print(ans.get(i)+" ");
        	}
        	

        }
        public static long pow(long n, long p,long mod) {
			if(p==0)
				return 1;
			if(p==1)
				return n%mod;
			if(p%2==0){
				long temp=pow(n, p/2,mod);
			return (temp*temp)%mod;
			}else{
				 	long temp=pow(n,p/2,mod);
				 	temp=(temp*temp)%mod;
				 	return(temp*n)%mod;
				 	
			}
		}
    
		        
		        
        public static int LCS(String a,String b){
        	int dp[][]=new int [a.length()+1][b.length()+1];
        	for(int i=0;i<a.length();i++){
        		for(int j=0;j<b.length();j++){
        			if(a.charAt(i)==b.charAt(j)){
        				dp[i+1][j+1]=1+dp[i][j];
        			}else{
        				dp[i+1][j+1]=Math.max(dp[i][j+1], dp[i+1][j]);
        			}
        		}
        	}
        	return dp[a.length()][b.length()];
        }
      
        public static String reverseString(String s) {
			StringBuilder sb = new StringBuilder(s);
			sb.reverse();
			return (sb.toString());
		}
  
    		       
// To Get Input
// Some Buffer Methods
 
    		     	public static void sort(long a[]){
    		     		Merge(a, 0, a.length-1);
    		     	}
    		    	public static void InputReader(InputStream stream1) {
    		    		stream = stream1;
    		    	}
 
    		    	private static boolean isWhitespace(int c) {
    		    		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    		    	}
 
    		    	private static boolean isEndOfLine(int c) {
    		    		return c == '\n' || c == '\r' || c == -1;
    		    	}
 
    		    	private static int read() {
    		    		if (numChars == -1)
    		    			throw new InputMismatchException();
    		    		if (curChar >= numChars) {
    		    			curChar = 0;
    		    			try {
    		    				numChars = stream.read(buf);
    		    			} catch (IOException e) {
    		    				throw new InputMismatchException();
    		    			}
    		    			if (numChars <= 0)
    		    				return -1;
    		    		}
    		    		return buf[curChar++];
    		    	}
 
    		    	private static int nextInt() {
    		    		int c = read();
    		    		while (isSpaceChar(c))
    		    			c = read();
    		    		int sgn = 1;
    		    		if (c == '-') {
	sgn = -1;
	c = read();
}
int res = 0;
do {
	if (c < '0' || c > '9')
	throw new InputMismatchException();
res *= 10;
res += c - '0';
    		    			c = read();
    		    		} while (!isSpaceChar(c));
    		    		return res * sgn;
    		    	}
 
    		    	private static long nextLong() {
    		    		int c = read();
    		    		while (isSpaceChar(c))
    		    			c = read();
    		    		int sgn = 1;
    		    		if (c == '-') {
	sgn = -1;
	c = read();
}
long res = 0;
do {
	if (c < '0' || c > '9')
	throw new InputMismatchException();
res *= 10;
res += c - '0';
    		    			c = read();
    		    		} while (!isSpaceChar(c));
    		    		return res * sgn;
    		    	}
 
    		    	private static String nextToken() {
    		    		int c = read();
    		    		while (isSpaceChar(c))
    		    			c = read();
    		    		StringBuilder res = new StringBuilder();
    		    		do {
    		    			res.appendCodePoint(c);
    		    			c = read();
    		    		} while (!isSpaceChar(c));
    		    		return res.toString();
    		    	}
 
    		    	private static String nextLine() {
    		    		int c = read();
    		    		while (isSpaceChar(c))
    		    			c = read();
    		    		StringBuilder res = new StringBuilder();
    		    		do {
    		    			res.appendCodePoint(c);
    		    			c = read();
    		    		} while (!isEndOfLine(c));
    		    		return res.toString();
    		    	}
 
    		    	private static int[] nextIntArray(int n) {
    		    		int[] arr = new int[n];
    		    		for (int i = 0; i < n; i++) {
    		    			arr[i] = nextInt();
    		    		}
    		    		return arr;
    		    	}
 
    		    	private static long[][] next2dArray(int n, int m) {
    		    		long[][] arr = new long[n][m];
    		    		for (int i = 0; i < n; i++) {
    		    			for (int j = 0; j < m; j++) {
    		    				arr[i][j] = nextLong();
    		    			}
    		    		}
    		    		return arr;
    		    	}
    		    	private static char[][] nextCharArray(int n,int m){
    		    		char [][]c=new char[n][m];
    		    		for(int i=0;i<n;i++){
    		    			String s=nextLine();
    		    			for(int j=0;j<s.length();j++){
    		    				c[i][j]=s.charAt(j);
    		    			}
    		    		}
    		    		return c;
    		    	}
 
    		    	private static long[] nextLongArray(int n) {
    		    		long[] arr = new long[n];
    		    		for (int i = 0; i < n; i++) {
    		    			arr[i] = nextLong();
    		    		}
    		    		return arr;
    		    	}
 
    		    	private static void pArray(int[] arr) {
    		    		for (int i = 0; i < arr.length; i++) {
    		    			pw.print(arr[i] + " ");
    		    		}
    		    		pw.println();
    		    		return;
    		    	}
 
    		    	private static void pArray(long[] arr) {
    		    		for (int i = 0; i < arr.length; i++) {
    		    			pw.print(arr[i] + " ");
    		    		}
    		    		pw.println();
    		    		return;
    		    	}
 
    		    	private static void pArray(boolean[] arr) {
    		    		for (int i = 0; i < arr.length; i++) {
    		    			pw.print(arr[i] + " ");
    		    		}
    		    		pw.println();
    		    		return;
    		    	}
 
    		    	private static boolean isSpaceChar(int c) {
    		    		if (filter != null)
    		    			return filter.isSpaceChar(c);
    		    		return isWhitespace(c);
    		    	}
 
    		    	private interface SpaceCharFilter {
    		    		public boolean isSpaceChar(int ch);
    		    	}
        		    }
    		    	 class Pair implements Comparable<Pair>{
	        				
	    					
	    					int start,end;
	    					Pair(int start,int end){
	    					
	    						this.start=start;
	    						this.end=end;
	    					
	    					}
	    					@Override
	    					public int compareTo(Pair o) {
	    				
	    							
	    					
	    						if(start!=o.start)
	    						return (start-o.start);
	    						else
	    							return end-o.end;
	    					}
	    					public int hashCode() {
	    							//int hu = (int) (x ^ (x >>> 32));
	    							//int hv = (int) (y ^ (y >>> 32));
	    							//int hw = (int) (mass ^ (mass >>> 32));
	    							//return 31 * hu + hv ;
	    						return 0;
	    						}
	    						public boolean equals(Object o) {
	    							Pair other = (Pair) o;
	    						//	return x == other.x && y == other.y;
	    						return false;
	    						}
	    				}
 

        		  