[{"Location":"82 Some Street | Gautham PS M1M 1M1"},{"Location":"82 Some Street | Gautham PS M1M 1M1"},{"Location":"82 Some Street | Gautham PS M1M 1M1"},{"Location":"83 Some Street | Gautham PS M1M 1M1"},{"Location":"84 Some Street | Gautham PS M1M 1M1"}]

db.collection.aggregate([{"$group":{"_id":"$Location","count":{"$sum":1}}},{"$match":{count:1}},{"$count":"uniqueAddresses"}])