USART Receive multiple characters


I am trying to recognize a number sent to USART:

If I send ‘123’ over USART to MCU then MCU receives only ‘3’ (the last character). Variable recv has uint8_t (unsigned integer) type. How could I receive the complete number (‘123’)?

I am using STM32L0 MCU and STM32CubeIDE environment.

Thank you.