Fix maxmimum length bug from -Wall

main.c

@@ -35,7 +35,7 @@ int main(){
 		char subnt_s[16];
 		char broadcast_addr[16];
 		char network_addr[16];
-		char usable_range[31];
+		char usable_range[33];
 		unsigned int subnt;
 		int this_prefix;
 		printf("How many hosts do you need on this network [%d]? ", i);