//akartik80

#include <iostream>
#include <cstdio>

#define null NULL
#define get getchar_unlocked
#define put putchar//_unlocked
#define ll long long int
#define pb push_back
#define mp make_pair
#define pd(x) printf("%d", x)
#define pdn(x) printf("%d\n", x)
#define plld(x) printf("%lld", x)
#define plldn(x) printf("%lld\n", x)
#define sd(x) scanf("%d", &x)
#define slld(x) scanf("%lld", &x)
#define ss(x) scanf("%s", x)
#define sc(x) scanf("%c", &x)
#define pc(x) printf("%c", x)
#define ps(x) printf("%s", x)
#define psn(x) printf("%s\n", x)
#define pf(x) printf("%f", x)
#define pfn(x) printf("%f\n", x)
#define plf(x) printf("%lf", x)
#define plfn(x) printf("%lf\n", x)
#define sf(x) scanf("%f", &x)
#define slf(x) scanf("%lf", &x)
#define mod 1000000007

using namespace std;

inline int scan() {
	int n = 0, sign = 1, ch = get();

	while (ch < 48 || ch > 57) {
		if (ch == '-') {
			sign = -1;
		}

		ch = get();
	}

	while (ch >= 48 && ch <= 57) {
		n = (n << 3) + (n << 1) + ch - 48;
		ch = get();
	}

	return n * sign;
}

int main() {
	int n, i;

	n = scan();

	int a[n] , b[n];

	for (i = 0; i < n; i++) {
        a[i] = scan();
        b[i] = scan();
	}

	for (i = 1; i < n; i++) {
        if (a[i] != a[i - 1]) {
            break;
        }
	}

	if (i == n) {
        printf("YES");
        return 0;
	}

	for (i = 1; i < n; i++) {
        if (b[i] != b[i - 1]) {
            break;
        }
	}

	if (i == n) {
        printf("YES");
        return 0;
	}

	printf("NO");
}