N = int(input())
A = [0,3,6,9]
ans  = 0
for i in range(10):
    for k in range(10):
        x = 10*i + k
        if 10<=x<=min(99,N) and x%3 ==0 and (i+k)%3 == 0:
            ans += 1
            
def trans(x):
    if x == 0:
        return A[0]
    string=""
    while x!=0:
        u,v=divmod(x,4)
        string=str(A[v])+string
        x=u
    return int(string)

for i in range(4**10):
    num = trans(i)
    if 100<=num<=N and num%3 ==0:
        ans += 1
        
print(ans)