N = int(input())
Nstr = str(N)

def dfs(s):
  if(int(s) > N):
    return 0
  
  ret = 1 if all(s.count(c) > 0 for c in '753') else 0
  for c in '753':
    ret+=dfs(s+c)
    
  return ret

print(dfs('0'))