This is a concurrent system problem. I don't understand why counter =- 1 ,2, 2 And also I don't understand the code and Could you account the ANSWER and CODE in detail? thank you so much

pidt pidi int counter 0i void handlerl (int sig) counter- printf("counter= %d ", counter); fflush (stdout)/* Flushes the printed string to stdout */ kill (pid, SIGUSR1); void handler2 (int sig) counter += 2; print f ( "counter exit (0) %d ", counter); = main() signal (SIGUSR1, handler1); if ( (pid = fork ( ) ) 0) { signal (SIGUSR1, handler2) kill (getppid), SIGUSR1); while (1) else pid_t pi int status; if ((p= wait ( & status)) > 0) { counter + 3; printf ( "counter- %d ", counter)