/in/foo.cc: In function 'int main()':
/in/foo.cc:8:24: error: 'ans' was not declared in this scope
  for(int i=1;i<=n;i++) ans+=abs(a[n/2]-a[i]);
                        ^~~
/in/foo.cc:9:8: error: 'ans' was not declared in this scope
  cout<<ans;
        ^~~