Write a function read_int that mimics system call 5 (but only for non-negative integers). The function needs no input parameters but should return the integer generated by the user key presses (appropriately stored onto the stack). To read in an integer, your function should listen for and read in MMIO keyboard inputs until either (a) the user hits the enter key or (b) 10 characters have been exceeded [since the largest possible signed 32 bit integer is 2147483647, which has 10 characters]. If the user inputs an invalid character such as a letter (e. g., ‘a’) or symbol (e. g., ‘$’), your function should return -1 to indicate that an invalid number has been entered. Along the same lines, if the user tries to enter a negative number (e. g., contains ‘-‘ character) or too large of a number (i. e., causes overflow), also have your function return -1. Lastly, if the user types no characters at all and hits the enter key, return -1. Here are some examples that you can use as test cases: