Problem:
Score : 100 points

Problem Statement

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.

Constraints

The length of S is between 1 and 10 (inclusive).

S is a string consisting of lowercase English letters.

Input

Input is given from Standard Input in the following format:

S

Output

If S is a Hitachi string, print Yes; otherwise, print No.

Sample Input 1

hihi

Sample Output 1

Yes

hihi is the concatenation of two copies of hi, so it is a Hitachi string.

Sample Input 2

hi

Sample Output 2

Yes

Sample Input 3

ha

Sample Output 3

No

Solution in Python (3.4.3) (judge verdict: Wrong Answer)

s = input()
result = 'No'
start = -2
end = -2
for i, c in enumerate(s):
  #print(i, c)
  if c == 'h':
    start = i
  elif c == 'i' and i == (start + 1):
    result = 'Yes'
    end = i
  elif c == 'i' and i == (end + 1):
    result = 'No'

print(result)