(30pts) Check if an expression is balanced by its parentheses or not. Sample expression: ((a+b) Sample Output: False Sample expression: (((a+b)+c)+d)+e Sample Output: True (30pts) Write a program to print out tower(n), Sample Output: tower (1) t ** tower (2) * / Opts) Given a list of number from 1 to N. The list has only one missing number. (within 1 to N ). Please find out which number is missing. (Sorting not allowed. O ( n ) algorithm required) Sample Input Sequence: [3,5,2,1] \# missing 4