import sys
input = sys.stdin.readline

N=int(input())
ANS=0
STRN=str(N)
LEN=len(STRN)

def calc(keta):
    ANS=0
    
    ni=int(STRN[keta])

    if keta==LEN-1:
        if ni<=2:
            return 1
        elif ni<=5:
            return 2
        elif ni<=8:
            return 3
        else:
            return 4

    if ni%3!=0:
        if ni<=2:
            return 1*pow(4,LEN-keta-1)
        elif ni<=5:
            return 2*pow(4,LEN-keta-1)
        elif ni<=8:
            return 3*pow(4,LEN-keta-1)
        else:
            return pow(4,LEN-keta)

    else:
        if ni==0:
            return calc(keta+1)
        elif ni==3:
            return calc(keta+1)+pow(4,LEN-keta-1)
        elif ni==6:
            return calc(keta+1)+2*pow(4,LEN-keta-1)
        else:
            return calc(keta+1)+3*pow(4,LEN-keta-1)
            
ANS=calc(0)-4

for i in range(10,min(N,100)+1):
    if i%3!=0:
        continue
    
    STR=str(i)
    flag=0

    for j in STR:
        if int(j)%3!=0:
            flag=1
    if flag and (int(STR[0])+int(STR[1]))%3==0:
        ANS+=1

print(ANS)