A fruit seller's code uses '246' for 'good sweet fruit', '698' for 'sweet yellow banana' and '327' for 'fruit ripe mango'. What is the code digit for 'good'?

The common word 'sweet' between the first two lines is the shared digit 6, and the common word 'fruit' between lines 1 and 3 is the shared digit 2. In '246' the remaining digit 4 stands for 'good'.