Help the SMS problem in M-Zone. Thank you!

Texting is outside the intranet. Sending messages to Unicom and PHS is outside the intranet. It's all 15 cents. Sending messages to mobile phones belongs to the intranet. It's 10 cent. You can handle 20 packs of 400, 30 packs of 600 and 50 packs 1000. These packages that send messages to China Unicom are also considered as short messages in the package. The SMS package is used up, and it's still 15 cents. There are also 150 SMS packages in 5 yuan and 10 yuan packages.