A palindrome is a symmetrical string, that is, a string read identically from left to right as well as from right to left. For example, ”a”、”aba”、“abba” are palindrome and “abc”、”aabb” are not.
Let’s define a new function f(s).
For some string s, f(s) is the length of the longest palindrome substring.
The first line of the input contains one integer n ------ the length of the string (1<=n<=10^5)
The second line of the input is the string.
If f(s) great than 1, print “YES” without quote
Else print “NO” without quote