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


#include <stdio.h>
#include <stdlib.h>

int main() {
    int w;
    int diff;
    int firsttime = 1;

    scanf("%d", &w);
    while (w--) {
	int thisDiff, a, b;
	scanf("%d%d", &a, &b);
	thisDiff = abs(a-b);
	if (firsttime) {
	    diff = thisDiff;
	    firsttime = 0;
	} else {
	    if (diff != thisDiff) {
		printf("no\n");
		return 0;
	    }
	}
    }
    printf("yes\n");
}