1. Problem Description

The four disciples of Tang Monk are on their journey to obtain the scriptures. A kind-hearted person gives them N buns. They need to divide the buns according to the following rules:

• Zhu Bajie has the largest appetite and must eat at least half.
• Sha Seng has to carry the luggage, so he must eat at least the remaining half.
• Sun Wukong needs to protect Tang Monk, so he must eat at least the remaining half as well.
• The buns cannot be cut.

How many buns can Tang Monk eat at most?

2. Input and Output

Input Method

• Use input() to read the input. Note that after reading, it is a string and needs to be processed manually.
• N is a positive integer (greater than or equal to 1).

Output Method

• A positive integer (greater than or equal to 0)
• Use print() to output.

Example Input and Output

# Input:
15
# Output:
1