N = int(input())

n = len(str(N))

from itertools import product

if N < 100:
    
    
    print(max(N // 3 - 3, 0))
    
else:
    
    ans = 100 // 3 - 3
    
    
    for i in range(3, n):
        
        ans += 3 * 4 ** (i - 1)
    
    
    
    for i in product('0369', repeat=n):
        
        if i[0] != '0':
            
            if int(''.join(i)) <= N:
                ans += 1
                
    
    print(ans)