give string s return number unique palindrome length subsequence snote multiple way obtain subsequence count oncea palindrome string read forwards backwardsa subsequence stre new string generate original string character delete change relative order remain charactersFor example ace subsequence abcde Example 1input s aabcaoutput 3explanation the 3 palindromic subsequence length 3 aba subsequence aabca aaa subsequence aabca aca subsequence aabcaexample 2Input s adcoutput 0explanation there palindromic subsequence length 3 adcexample 3input s bbcbabaoutput 4explanation the 4 palindromic subsequence length 3 bbb subsequence bbcbaba bcb subsequence bbcbaba bab subsequence bbcbaba aba subsequence bbcbaba Constraints3 slength 105s consist lowercase english letter