Fix wrong print format

packet-exchange/src/server.c

 #include <arpa/inet.h>
 #include <errno.h>
 #include <error.h>
+#include <inttypes.h>
 #include <netdb.h>
 #include <netinet/in.h>
 #include <pthread.h>
@@ -111,7 +112,7 @@ int main(int argc, char *argv[]) {
   for (;;) {
     usleep(main_param.refresh_rate);
 
-    printf("%ld  -  %ld, %ld  (%d)\n",
+    printf("%" PRIu64 "  -  %" PRIu64 ", %" PRIu64 "  (%d)\n",
            param.stats.max_interval - param.stats.min_interval,
            param.stats.min_interval, param.stats.max_interval,
            param.stats.packets_received);