Determines whether a substitution is even or odd. (8 characters)

Determines whether a permutation is even or odd.
Here, we consider the permutation of the sequence 12345678.
This determines whether the 8-character permutation σ is even or odd.
If even, sgn(σ) = 1 (one)
If odd, sgn(σ) = -1 (minus one)
Accordingly,
the program outputs 1 or -1 as the result.
A permutation that can be expressed as the product of an even number of transpositions is an even permutation,
while a permutation that can be expressed as the product of an odd number of transpositions is an odd permutation.
If the permutation is even, the parity is determined to be even, and 1 is output.
If the permutation is odd, the parity is determined to be odd, and -1 is output.
Determining whether a permutation is even or odd is sometimes used in the definition of determinants.
In the input field, enter the sequence of numbers whose parity you want to check (the string of numbers resulting from permuting 12345678).
In permutation notation, this is often written in the bottom row.
For example, if you want to check the parity of 87651234—which is the result of permuting the digits of 12345678—
enter 1=8, 2=7, 3=6,Input 4=5, Input 5=1, Input 6=2, Input 7=3, and Input 8=4.
The program will output the parity determination results.