Ah, common issue. When that happens, you just start using your toes.

Pah, mathematicians and their generally applicable pure approach to solutions and fancy modulus operations, who needs 'em? Computing is applied and we always work with well-defined finite precision. Granted, writing the boilerplate for all possible 64 bit integers is a bit laborious, but we’re programmers! That’s what code generation is for.

Alternatively, you could use a browser instead of an advertisement delivery app.