Please compute the sum of two given n-bit binary numbers.
The first line of the input file contains a positive integer t indicating the number of test cases. The first line of each test case is a positive integer n denoting the length of bits. The second and third lines are the two n-bit binary numbers. The first bit of each binary number is always 0, which guarantees that the sum of the two binary numbers can still be expressed as an n-bit binary number.
Case1 : t<=100, n<=100
Case2 : t<=200, n<=1000
Case3 : t<=300, n<=5000
Case4 : t<=400, n<=10000
For each test case, your program should print the sum in the same format as the binary numbers given in input.
Notice that each answer is ended with a newline character.