[Python] Mod operator in Free Pascal gives a different result than expected

The mod operator in Free Pascal does not produce the results I would expect.

This can be demonstrated by the program below whose output does not agree with the result of the same calculation in Python (or Google).

program test(output);

var
a, b, c: longint;

begin
a := -1282397916;
b := 2147483647;
c := a mod b;
writeln (c:16);
end.


-1282397916


Compare this to the output of the Python script below which gives the result I expected.

#!/usr/bin/python

a = -1282397916
b = 2147483647
c = a % b
print (c)


865085731


This is the same as the result as that obtained by pasting the following text into Google (and when using the mod operator in VAX‑Pascal).

(-1282397916 % 2147483647)


The question is: Why does Free Pascal behave differently? And how do I get the same result as that obtained when using the mod operator in Python?

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