How to get the only the used heap memory details usage from jboss-cli in EAP 6/7

Issue

• How to grep the only the used heap memory details usage from JBoss CLI.
• How to get a particular string value from JBoss CLI.
• I execute jboss-cli to get the heap memory usage, the output seems the collections of init, used, committed as below example.How can I get the value of used only ?

D:\jboss-eap-6.3\bin>jboss-cli.bat --connect --command="/core-service=platform-mbean/type=memory/:read-attribute(name=heap-memory-usage)"
{
    "outcome" => "success",
    "result" => {
        "init" => 1073741824L,
        "used" => 348142800L,
        "committed" => 1051721728L,
        "max" => 1051721728L
    }
}