def check(n):
    ok = 1
    s = str(n)
    L = len(s)

    for i in range(L):
        if s[i] != s[L-1-i]:
            ok = 0

    return ok

def main():
    A = 10**9+1

    n = int(input())

    now = A
    ct = 0
    while now < n:
        ct += check(now)
        now += A

    return ct

if __name__ == '__main__':
    print(main())