/in/foo.cc: In function 'int To_Ten(char)':
/in/foo.cc:70:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/in/foo.cc: In function 'char To_K(int, int)':
/in/foo.cc:23:7: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
  char c;
       ^
/in/foo.cc: In function 'bign change(int, int)':
/in/foo.cc:47:14: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
   res.a[i++] = To_K(k % r, r);
   ~~~~~~~~~~~^~~~~~~~~~~~~~~~
/in/foo.cc: In function 'bign Mul(bign, int)':
/in/foo.cc:84:18: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
   res.a[res.n++] = To_K(carry % r, r);
   ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~
/in/foo.cc:79:18: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
   res.a[res.n++] = To_K(temp % r, r);
   ~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~