Value user_num is read from input. Write a while loop that reads values from input and casts the values into integers, until the integer -1 is read. In each iteration: Update int_sum with the sum of int_sum and user_num. Read the next integer from input. Integer -1 should not be included in the sum. int_sum = 0 user_num = int(input()) ''' Your code goes here ''' print(int_sum)