Java question about regular expressions

Consider the following regular expression inside a Java String: String expression = "[a-k] + [0-9] + [1-z] +" Write four public strings s1m, s2m, s3n, s4n as public String s1m = "ellipsis"; public String s2m = "ellipsis"; public String s3n = "ellipsis"; public String s4n = "ellipsis"; where ellipsis is a string on which in the case of s1m and s2m, the expression matches() in the case of s3n and s4n, the expression does not match. s1 m and s2m must be of different lengths, and must not contain the same character twice. s3n and s4n must also be of different lengths and must not contain the same character twice