/in/foo.cc: In function 'int main()':
/in/foo.cc:22:12: warning: unused variable 'len' [-Wunused-variable]
  int i,n,j,len=1,ans;
            ^~~
/in/foo.cc: In function 'int qsort(int, int)':
/in/foo.cc:20:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^