no3times = {"1", "2", "4", "5", "7", "8"}
N = int(input())
ids = range(1, N+1)
Xs = [i for i in ids if (i % 3 == 0) and (len(str(i)) == 2 or (len(str(i)) > 2 and set(str(i)).isdisjoint(no3times)))]
#print(Xs)
print(len(Xs))