how can I input into a cell a number with this limits:

1° number value from 1 to 9

2° number value from 2 to 10

but 2° number > 1° number (or 1° number < 2° number)

i.e. ok:

12 (ossia 1 and 2)

39 (ossia 3 and 9)

710 (ossia 7 and 10)

910 (ossia 9 and 10)

KO:

98 (ossia 9 and 8)

99 (ossia 9 and 9)

109 (ossia 10 and 9)

Tia. Maurizio