#1300 · String Power

The K^{th} power string of a string S is a string T formed by writing S string K times consecutively. For example, the 3^{rd} power string of the string "abc" is the string "abcabcabc".

Given an integer K and two strings S and T. Check if T is the K^{th} power string of S.

Consists of 3 lines:

• The first two lines respectively contain strings S and T
• The last line contains the integer K.

If T is the K^{th} power string of S, print YES. Otherwise, print NO.