S = input()

'''
357 375 537 573 735 753 
3357 3375 3537 3573 3735 3753 
5357 5375 5537 5573 5735 5753 
3357,3375,3537,

3けた　、4けた 5 ,6, 7, 8
6,18,54,162,486, 8
sum = [2 * 3,2 * 3 * 3,]
'''

N = len(S)
list375 =['3','5','7']

for i in range(N):
    if i ==0:
        continue
    else:
        targetList = list375[:]
        for l in targetList:
            list375.append('3' + l)
            list375.append('5' + l)
            list375.append('7' + l)

result = [i for i in list(set(list375)) if int(i) < int(S) and i.count('3') !=0 and i.count('5') !=0 and i.count('7') !=0]
#print(result)
print(len(result))


'''
def judge753():
    if keta[0] < 3:
        return 0
    if keta[0] < 5:
        if keta[1] < 3:
            return 0
        if keta[1] < 5:
            if keta[2] < 5:
                return 0
            if keta[2] < 7:
                return 1
            return 2
        if keta[1] < 7:
            
        return sum[len(S)-1]
    if keta[0] < 7:
        if keta[1] < 3:
            return sum[len(S)-1] + sum[len(S)-2]
        if keta[1] < 5:
            if keta[2] < 5:
        
        return sum[len(S)-1]
        
print(min(absList))
'''
