Fix segfault without arg in 2001/cheong

2001/cheong/README.md

@@ -15,8 +15,9 @@ make
 [Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) fixed this to work with
 clang by adding another function that is allowed to have a third arg as an int,
 not a `char **`. He chose pain() because it's a four letter word that would
-match the format and because it's pain that clang forces this. :-) Thank you
+match the format and because it's pain that clang forces this. :-) He also fixed
-Cody for your assistance!
+a segfault in the case that no arg is specified. Thank you Cody for your
+assistance!
 
 
 ### To run:

2001/cheong/cheong.c

@@ -11,4 +11,4 @@ c=o+     (D[I]+82)%10-(I>l/2)*
 :!(o=pain(c/10,O,I-1))*((c+999
 )%10-(D[I]+92)%10);}return o;}
 int main(int o,char **O)     {
-return pain(o, O, l);	     }
+return O[1]?pain(o, O, l):1; }