/in/foo.c: In function 'main':
/in/foo.c:11:3: warning: statement with no effect [-Wunused-value]
   for(b;b*10+a%10<=a;a/=10){
   ^~~
/in/foo.c:6:6: warning: variable 'c' set but not used [-Wunused-but-set-variable]
  int c;
      ^
/in/foo.c:7:3: warning: 'a' is used uninitialized in this function [-Wuninitialized]
  c=a;
  ~^~