# coding: utf-8
# Your code here!
n = int(input())

cnt = 0

for i in range(10, min(100, n + 1)):
    cnt = cnt + 1 if (int(str(i)[0]) + int(str(i)[1])) % 3 == 0 and i % 3 == 0 else cnt
    
if n > 100:
    numList = ['0', '3', '6', '9']
    for a in range(4):
        for b in range(4):
            for c in range(4):
                for d in range(4):
                    for e in range(4):
                        for f in range(4):
                            for g in range(4):
                                for h in range(4):
                                    for i in range(4):
                                        s = int(numList[a] + numList[b] + numList[c] + numList[d] + numList[e] + numList[f] + numList[g] + numList[h] + numList[i])
                                        if s <= n and s > 100:
                                            cnt += 1
    
print(cnt)