The figure shown on the left is left-right symmetric as it is possible to fold the sheet of paper along a vertical line, drawn as a dashed line, and to cut the figure into two identical halves. The figure on the right is not left-right symmetric as it is impossible to find such a vertical line. Write a program that determines whether a figure, drawn with dots, is left-right symmetric or not. The dots are all distinct. Input The input consists of T test cases. The number of test cases T is given in the first line of the input file. The first line of each test case contains an integer N , where N (1 ≤ N ≤ 1, 000) is the number of dots in a figure. Each of the following N lines contains the x-coordinate and y-coordinate of a dot. Both x-coordinates and y-coordinates are integers between −10, 000 and 10, 000, both inclusive. Output Print exactly one line for each test case. The line should contain ‘YES’ if the figure is left-right symmetric, and ‘NO’, otherwise. Sample Input 3 5 -2 5 00 65 40 23 4 23 04 40 00 4 5 14 6 10 5 10 6 14
2/2 Sample Output YES NO YES