change

exp1/task62.c

@@ -3,6 +3,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <semaphore.h>
 
 int cnt = 0;
 sem_t mutex;

exp1/task63.c

@@ -0,0 +1,7 @@
+#include <pthread.h>
+#include <time.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <semaphore.h>
+