zcalcu: Chat & Calculator

zcalcu is a 2 in 1 chat and calculator app. This app can be swapped between a chat application and a simple calculator. Its main features: -Setting the app type in calculator mode by calculate default secret key "17-08-1945". -Setting the secret key. -Change app type and icon between calculator and chat. -Chat a friend by a username with picture, and text. -Automatically disappearing recent message in 2 days