n = int(input())
ans = 0
threes = 0
for i in range(10, min(100, n+1)):
    p, q = divmod(i, 10)
    if (p + q) % 3 == 0:
        ans += 1
        if p % 3 == 0:
            threes += 1
if n < 100:
    print(ans)
    exit()
ans -= threes + 4
n = str(n)
dp = [[0, 0] for _ in range(len(n) + 1)]
dp[0][0] = 1
for i, x in enumerate(map(int, n)):
    if x == 0 or x == 3 or x == 6 or x == 9:
        dp[i+1][0] += dp[i][0]
    dp[i+1][1] += (x + 2) // 3 * dp[i][0]
    dp[i+1][1] += dp[i][1] * 4
ans += sum(dp[len(n)])
print(ans)