// Problem idea by Albert Lai  <trebla@cs.utoronto.ca>
// Problem written by Albert Lai
// This solution written by Thomas Tang


import java.io.*;
import java.util.*;

public class ground
{
    static StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));

    static int getint() {
	try {
	    in.nextToken();
	    return (int)in.nval;
	}
	catch (Exception e) {
	    throw new InternalError();
	}
    }


    public static void main(String[] args) {
	int w;
	int diff = 0;
	boolean firsttime = true;
        
	for (w = getint(); w > 0; w--) {
	    int a = getint();
	    int b = getint();
	    int thisdiff = a - b;
	    if (firsttime) {
		diff = thisdiff;
		firsttime = false;
	    } else {
		if (diff != thisdiff) {
		    System.out.println("no");
		    return;
		}
	    }
	}
	System.out.println("yes");
    }
}