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

int main() {

    int q;
    scanf("%d", &q);
    
    while(q--){
        
        int n;
        scanf("%d", &n);
        
        int rect[n][2];        
        int i,j;
        
        for(i=0; i<n; i++){
            for(j=0; j<2; j++)
                scanf("%d", &rect[i][j]);
        }
        
        int max_x = rect[0][0], min_x = rect[0][0];
        int max_y = rect[0][1], min_y = rect[0][1];
        int max = 0, min = 0;
        
        for(i=0; i<n; i++){
            if(rect[i][0] > max_x + max_y)
                max_x = rect[i][0], max_y = rect[i][1], max = i;
            if(rect[i][0] < min_x + min_y)
                min_x = rect[i][0], min_y = rect[i][1], min = i;
        }
//        printf("x   %d %d \n",max_x,min_x);
//        printf("y   %d %d \n",max_y,min_y);
        
        int flag = 1;
        
        for(i=0; i<n; i++){
            if(rect[i][0] != max_x && rect[i][0] != min_x) flag = 0;
            if(rect[i][1] != max_y && rect[i][1] != min_y) flag = 0;
        }
        
        if(n <= 3) flag = 1;
        
        flag ? printf("YES\n") : printf("NO\n");                
        
    }
    
    return 0;
}