-bash-4.2$ ./mailbox 4
0 2
5 2
-1 2
Invalid value.
7 0
Invalid recipient id.
7 5
Invalid recipient id.
10 4
7 1
2 1
3 2
The result from thread 1 is 9 from 2 operations during 2 secs.
The result from thread 3 is 0 from 0 operations during 2 secs.
The result from thread 4 is 10 from 1 operations during 2 secs.
The result from thread 2 is 8 from 3 operations during 3 secs.
-bash-4.2$ ./mailbox 4 nb
0 2
5 2
-1 2
Invalid value.
7 0
Invalid recipient id.
7 5
Invalid recipient id.
10 4
7 1
2 1
3 2
The result from thread 3 is 0 from 0 operations during 0 secs.
The result from thread 4 is 10 from 1 operations during 1 secs.
The result from thread 1 is 9 from 2 operations during 2 secs.
The result from thread 2 is 8 from 3 operations during 3 secs.
-bash-4.2$ ./mailbox 4
6 4
a 5
The result from thread 2 is 0 from 0 operations during 0 secs.
The result from thread 1 is 0 from 0 operations during 0 secs.
The result from thread 3 is 0 from 0 operations during 0 secs.
The result from thread 4 is 6 from 1 operations during 1 secs.