Super India Ltd issued 75,000 equity shares. The whole of the issue was underwritten as follows : 

A ---- 50%; 

B ---- 25%; 

C ---- 25%. 

Applications for 60,000 shares were received in all, out of which applications for 15,000 shares had the stamp A, those for 7,500 shares that of B, and those for 15,000 shares that of C. The remaining applications for 22,500 shares did not bear any stamp. Determine the liability of the underwriters.