Giới thiệu: Đây là đề thi ICPC

A file name consists of 2 parts: base name and extension name, separated by a dot character. For example, Python source code files have extension name "py", documents have extension name "doc" or "docx". In Windows OS, file names are case insensitive. Please help Salmon: Write a program to input a file name as string and check whether it is considered Python source code file in Windows or not

Input

Only one line contain file name S (1 ≤ |S| ≤ 128). File name will only contain (a->z, A->Z, . and _).

Output

If file is a python file, print "yes", otherwise "no"

Examples

Input

abc.py

Output

yes

Input

abc.bin

Output

no