How to get keys and value if not know name of keys

This is my JSON . I want to get time keys (9:00,13:00,16:00) but if I don't know this how I get them to checking end time in child

{ "Monday" : { "09:00" : { "Attendance" : { "1" : { "560111222333" : 1, "Date" : "11/05/20" }, "dummy" : "dummy" }, "End" : "12:00", "Late" : "09:15", "Student" : { "560111222333" : { "FingerprintID" : 1, "Name" : "Saranphat moolpho" }, "560333222111" : { "FingerprintID" : 2, "Name" : "Pattanun punnamsai" } }

}, "13:00" : { "Attendance" : { "1" : { "560111222333" : 1, "Date" : "11/05/20" }, "dummy" : "dummy" }, "End" : "15:00", "Late" : "13:15", "Student" : { "560111222333" : { "FingerprintID" : 1, "Name" : "Saranphat moolpho" }, "560333222111" : { "FingerprintID" : 2, "Name" : "Pattanun punnamsai" } } }, "16:00" : { "Attendance" : { "1" : { "560111222333" : 1, "Date" : "11/05/20" }, "dummy" : "dummy" }, "End" : "18:00", "Late" : "16:15", "Student" : { "560111222333" : { "FingerprintID" : 1, "Name" : "Saranphat moolpho" }, "560333222111" : { "FingerprintID" : 2, "Name" : "Pattanun punnamsai" } } } }, "State" : "1 5603051624158" }

If you are using the JSON library to parse this, you need to iterate over all your key/value pairs with begin()/end() example