# coding utf-8

s = str(input())

# 入力単語長が奇数ならNO
if len(s) % 2 != 0:
    print("NO")
else:
    print(s[:(len(s)/2)])
    print(s[(len(s)/2):])
    if s[:(len(s)/2)] == s[(len(s)/2):]:
        print("YES")
    else:
        print("NO")