# coding: utf-8

# 1 < n < Nの10**9+1の倍数のリストを返す
def multiple(N):
    multiList = []
    tmp  = N / (10**9 + 1)
    for t in range(tmp):
        multiList.append((10**9+1)*(t+1))

    return multiList

def palindrome(list):
    palindromeList = []
    list = map(str, list)
    for t in list:
        if t == t[::-1]:
            palindromeList.append(t)

    return palindromeList

if __name__ == "__main__":
    N = ""
    while N == "":
        N = raw_input()

    # 倍数判定
    multiList = multiple(int(N))
    # 回文判定
    palindromeList = palindrome(multiList)

    print len(palindromeList)