import sys
input = sys.stdin.readline

def dfs(d, now):
    global ans
    
    if d==10:
        if 10<=now<=N:
            ans += 1
        return
    
    for n in [0, 3, 6, 9]:
        dfs(d+1, 10*now+n)

N = int(input())
ans = 0
dfs(0, 0)

for i in range(10, 100):
    if i%3==0 and (i//10%3!=0 or i%10%3!=0) and i<=N:
        ans += 1

print(ans)