Maximum value: the maximum value, less than or equal to; There are four at most, that is, less than or equal to four.

Do not exceed: maximum is the same as maximum, less than or equal to; For example, no more than four, that is, at most or at most four, that is, less than or equal to four.

Not less than: greater than or equal to, equal to at least; For example, not less than two, that is, more than or equal to two.