How can I go from a grammar for a shift reduce parser to a context free grammar?

In computer science, an LR parser is a type of bottom-up parser for context-free grammars that is very commonly used by computer programming language compilers (and other associated tools). LR parsers read their input from Left to right and produce a Rightmost derivation (hence LR, compare with LL parser). The term "LR(k) parser" is also used; here the k refers to the number of unconsumed "look ahead" input symbols that are used in making parsing decisions. Usually k is 1 and is often omitted. A context-free grammar is called LR(k) if there exists an LR(k) parser for it.