/in/foo.cc: In function 'void qsort(int, int)':
/in/foo.cc:8:5: error: 'a' was not declared in this scope
 mid=a[(l+r)/2];
     ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:29:6: error: 'a' was not declared in this scope
 cin>>a[i];
      ^
/in/foo.cc:32:9: error: 'c' was not declared in this scope
 int mid=c[(1+n)/2];
         ^
/in/foo.cc:34:8: error: 'a' was not declared in this scope
 s+=abs(a[i]-mid);
        ^