Getting empty property error while traversing json using php

I am using Apache Solr Engine to provide suggestions to the user based on the input keyword.

I have a json response in the following format.

{
    "suggest": {
        "mySuggester": {
            "A Ga": {
                "numFound": 2,
                "suggestions": [
                {
                    "term": "<b>A Ga</b>me of Thrones",
                    "weight": 0,
                    "payload": "Book"
                },
                {
                    "term": "<b>A Ga</b>teway to Heaven",
                    "weight": 0,
                    "payload": "Book"
                }]
            }
        }
    }
}

The Key A Gais user input, that is, based on this key, the suggestions are provided. Now Solr returns this JSON which is stored in my $response variable in php and the key A Ga is contained in the variable $inp.

In my code, there is a line which is,

$noOfSuggestions =  $response->suggest->mySuggester->$inp->numFound;

I am getting a cannot access empty property error at this line. Is my usage of $inp correct?

Thanks!

EDIT: This is var_dump($response);

object(Apache_Solr_Response)#60 (5) { ["_response":protected]=> object(Apache_Solr_HttpTransport_Response)#50 (5) { ["_statusCode":"Apache_Solr_HttpTransport_Response":private]=> int(200) ["_statusMessage":"Apache_Solr_HttpTransport_Response":private]=> string(2) "OK" ["_mimeType":"Apache_Solr_HttpTransport_Response":private]=> string(10) "text/plain" ["_encoding":"Apache_Solr_HttpTransport_Response":private]=> string(5) "UTF-8" ["_responseBody":"Apache_Solr_HttpTransport_Response":private]=> string(511) "{"responseHeader":{"status":0,"QTime":2},"suggest":{"mySuggester":{"A Ga":{"numFound":2,"suggestions":[{"term":"A Game of Thrones","weight":0,"payload":"Book"},{"term":"A Gateway to Heaven","weight":0,"payload":"Book"}]}}}} " } ["_isParsed":protected]=> bool(false) ["_parsedData":protected]=> NULL ["_createDocuments":protected]=> bool(true) ["_collapseSingleValueArrays":protected]=> bool(true) }