Schedule cfl

In schedule CFL:

In AY2009-10 I made a loss of 35000

In AY2010-11 I made a profit of 18000

In AY2011-12 I made a loss of 2000

So my total earlier losses is (35000-18000+2000)=19000.

But it does not allow negative values. So how do I depict this? If I leave AY2010-11 blank then total earlier losses is shown as 37000, which is wrong.

Can you please help me by suggesting how to handle this?

Thanks,

Subhra Majumder.