N = int(input())
def dfs(s):
    if int(s) > N:
        return 0
    else:
        if '7' in s and '5' in s and '3' in s:
            ret = 1
        else:
            ret = 0
        for c in '357':
            ret += dfs(s + c)
        return ret
print(def("0"))