It would superficially appear to me that this might not be a good application of this tool.   The base-structure of this string appears to be that it consists of s:integer:string, and this, to my way of thinking, is not the sort of request that is well-suited to, nor that particularly needs, the services of a parser.   In what context do strings of this nature appear in your input data?   Please tell us more about the surrounding context of your problem.