import sys
#input = sys.stdin.readline
input = sys.stdin.buffer.readline #文字列はダメ
#sys.setrecursionlimit(1000000)
#import bisect
#import itertools
#import random
#from heapq import heapify, heappop, heappush
#from collections import defaultdict 
#from collections import deque
#import copy
#import math
#from functools import lru_cache
#@lru_cache(maxsize=None)
#MOD = pow(10,9) + 7
#MOD = 998244353
#dx = [1,0,-1,0]
#dy = [0,1,0,-1]

def main():
    N = int(input())
    ans = 0
    MAX = pow(10,5) + 100
    for i in range(1,MAX):
        v = str(i) + str(i) + str(i)
        v = int(v)
        if v <= N:
            ans += 1
    print(ans)

if __name__ == '__main__':
    main()