Score : 100 points
A Hitachi string is a concatenation of one or more copies of the string hi.
For example, hi and hihi are Hitachi strings, while ha and hii are not.
Given a string S, determine whether S is a Hitachi string.
Input is given from Standard Input in the following format:
S
If S is a Hitachi string, print Yes; otherwise, print No.
hihi
Yes
hihi is the concatenation of two copies of hi, so it is a Hitachi string.
hi
Yes
ha
No