I have a **list** Allflights of object type FLightInfo. 

If an object from the list has the same flightNumber and takeofftime. 
I want to consolidate those entries and add their user count

**Example:** This is my list: 

* FlightNumber 123 Takeoff 12:00 Users 5
* FlightNumber 256 Takeoff 3:00 Users 6
* FlightNumber 123 Takeoff 12:00 Users 8
* FlightNumber 651 Takeoff 5:00 Users 3

I want the **output** to be like:

```
FlightNumber 123  Takeoff 12:00 Users 13
FlightNumber 256  Takeoff 3:00  Users 6  
FlightNumber 651  Takeoff 5:00  Users 3

```

My source code:

```
struct FlightInfo
        {
            public string FlightNumber { get; set; }
            public string Takeoff_time { get; set; }
            public string Landing_time { get; set; }
            public int UserCount { get; set; }
}

static List<FlightInfo> allFlights = new List<FlightInfo>();

//I read several files using multi-threading and create a FlightInfo object   
//and add it to the allFlights list

allFlights.Add(buildFlight(FlightNumber, Origination, Destination, Takeoff_time, Landing_time, UserCount);

//This is what I need to do
//if FlightNumber && testTakeOff object attributes are the same 
// I want to consolidate those entries and add the UserCount from those entries

```