#include #include #include #include #include #include #include #include #include using namespace std; #define ff first #define ss second #define _N 100005 #define mk make_pair #define pb push_back map Z, W; int main () { int n, i, x, y, q = 0; scanf ("%d", &n); for (i = 0;i < n; i ++) { scanf ("%d%d", &x, &y); Z[x] ++; W[y] ++; } for (i = -11;i <= 11; i ++) if (Z[i] == n || W[i] == n) return !printf ("YES"); printf ("NO"); return 0; }