Negative Lookbehind(?<!\S) \Sany character that is not Unicode whitespace
INTthe literal text INT (case sensitive) .any Unicode character (except for line terminators)
ESTthe literal text EST (case sensitive) .any Unicode character (except for line terminators)
Cthe literal C (6710 / 1038 / 4316) (case sensitive)
.any Unicode character (except for line terminators)
Sthe literal S (8310 / 1238 / 5316) (case sensitive)
.any Unicode character (except for line terminators)
\Sany character that is not Unicode whitespace
g modifier: global. Finds all matches instead of stopping after the first