Calculate the maximum of real numbers

Implement a program that reads 12 real numbers and calculates the maximum. Run the following test cases to test your program:

test case ID	inputs	expected outputs
1	12.2, 6.0, 3.3, 4, 5, 6.5, 7, 8, 9, 3.3, 11, 12.2	12.2
2	-1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12	-1
3	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0	0
4	12.4, 21.005, -3.67, 4.43, 5.56, 4.2, 7, 8.3, -91.3, -1.0, 32.4, 12.1	32.4

Insist that the students test their programs by giving them example
test cases in a table.