func main()
	var s: []char :: cui@input()
	var n: int :: ^s
	var ans: int :: 0
	for i(0, n - 1)
		var cnt: int :: 1
		for j(1, n)
			var l: int :: i - j
			var r: int :: i + j
			if(l < 0 | n <= r)
				break j
			end if
			if(s[l] = s[r])
				do cnt :+ 2
			end if
		end for
		do ans :: [ans, cnt].max()
	end for
	for i(0, n - 2)
		var cnt: int :: s[i] = s[i + 1] ?(2, 0)
		for j(1, n)
			var l: int :: i - j
			var r: int :: i + j + 1
			if(l < 0 | n <= r)
				break j
			end if
			if(s[l] = s[r])
				do cnt :+ 2
			end if
		end for
		do ans :: [ans, cnt].max()
	end for
	do cui@print("\{ans}\n")
end func