Minimum Operations to Palindrome

You are given a string S. Your task is to determine the minimum number of operations required to convert S into a palindrome. In one operation, you can change any character to any other character. A palindrome is a string that reads the same forward and backward.

For example, the string abca can be transformed into abba with just one operation by changing the third character. Use this property to decide the number of changes needed.

inputFormat

The input is provided via standard input (stdin) as a single line containing the string S.

outputFormat

Output the minimum number of operations needed to transform S into a palindrome on the standard output (stdout).

abca

1