using System;

using System.Linq;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        const string FileContent1 = 

@"--- 10.0.0.6 ping statistics ---

50 packets transmitted, 49 packets received, 2% packet loss

round-trip min/avg/max = 20.917/70.216/147.258 ms

1466786342

PING 10.0.0.6 (10.0.0.6): 56 data bytes

​

--- 10.0.0.6 ping statistics ---

50 packets transmitted, 50 packets received, 0% packet loss

round-trip min/avg/max = 29.535/65.768/126.983 ms

1466786391";

        const string FileContent2 = 

@"--- 10.0.0.6 ping statistics ---

50 packets transmitted, 49 packets received, 2% packet loss

round-trip min/avg/max = 20.917/70.216/147.258 ms

1466786342

PING 10.0.0.6 (10.0.0.6): 56 data bytes

​

--- 10.0.0.6 ping statistics ---

50 packets transmitted, 50 packets received, 0% packet loss

round-trip min/avg/max = 29.535/65.768/126.983 ms

1466786391

PING 10.0.0.6 (10.0.0.6): 56 data byte

​

--- 10.0.0.6 ping statistics ---

50 packets transmitted, 44 packets received, 12% packet loss

round-trip min/avg/max = 30.238/62.772/102.959 ms

1466786442

PING 10.0.0.6 (10.0.0.6): 56 data bytes";

        var logBlockPattern = new Regex(@"(^---.*ping statistics ---$)\s+"

                                      + @"(^.+packets transmitted.+packets received.+packet loss$)\s+"

                                      + @"(^round-trip min/avg/max.+$)\s+"

                                      + @"(^\d+$)\s*"

                                      + @"(^PING.+$)?",

                                        RegexOptions.Multiline);

        var logBlocks1 = logBlockPattern.Matches(FileContent1).Cast<Match>().ToList();

        var logBlocks2 = logBlockPattern.Matches(FileContent2).Cast<Match>().ToList();

        var mergedLogBlocks = logBlocks1.Concat(logBlocks2.Where(lb2 => logBlocks1.All(lb1 => lb1.Groups[4].Value != lb2.Groups[4].Value)));

        var mergedLogContents = string.Join("\n\n", mergedLogBlocks);

        Console.WriteLine(mergedLogContents);

    }

}