Square string

The string s is a square if it has the form AA, where A is some non-empty string. In other words, a square is a string that is a concatenation of two copies of the same non-empty string. For example, the strings "aa", "zqzq" and "treetree" are squares.

Determine if the given string is a square string.

Input

One string of length no more than 100.

Output

Print yes if the input string is a square string and no otherwise.

Examples