#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int max_n = 100;

ll arr[max_n][2];

int main()
{
    ll t, i, j, n, m;

    scanf("%lld", &n);

    for(i=0;i<n;++i)
    scanf("%lld %lld", &arr[i][0], &arr[i][1]);

    bool flag = false;

    for(j=0;j<2;++j)
    {
        for(i=0;i<n-1;++i)
        {
            if(arr[i][j]!=arr[i+1][j])
            break;
        }

        if(i==n-1)
        flag = true;
    }

    if(flag)
    printf("YES");
    else
    printf("NO");

    return 0;
}