Petya loves lucky numbers. Everybody knows that lucky numbers are positive integers whose decimal representation contains only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

One day Petya dreamt of a lexicographically *k*-th permutation of integers from 1 to *n*. Determine how many lucky numbers in the permutation are located on the positions whose indexes are also lucky numbers.
The first line contains two integers *n* and *k* (1 ≤ *n*, *k* ≤ 10<sup class="upper-index">9</sup>) — the number of elements in the permutation and the lexicographical number of the permutation.
7 4
1
4 7
1
7 1
2
7 5040
1
10 1023
0
7 7477
-1
10 10000
1
3 7
-1
27 1
2
40 8544
2
47 1
4
47 8547744
3
50 1000000000
4
64 87
4
98 854555
6
100 1
6
9985 5888454
30
1 1
0
1 2
-1
2 1000000000
-1
10 1000000000
-1
20 1000000000
2
777777 1
126
777777 2
125
777474 10000
120
1000000000 1
1022
777777777 5
1021
777777777 1
1022
777477774 1
989
444747744 1000000000
554
475 88555458
8
12 855448
1
20 1000000000
2
47 99998544
2
49 1000000000
2
854459 95554455
126
77777779 1000000000
508
77 47
5
6999 85488877
22
7479 58884598
24
1000000000 1000000000
1022
7 1000
0
7 124
1
7 2048
1
7 3001
1
7 127
1
7 980
1
7 5000
0
7 4095
2
7 3856
0
7 5032
0
7 4999
0
2 3
-1
2 4
-1
7 985
1
4 25
-1
6 121
1
11 39916801
-1
29 1000000000
2
10 4589
1
10 100000
1
10 98564
1
10 1
2
10 100000009
-1
def lucky(x):
    s=str(x)
    return s.count('4')+s.count('7')==len(s)
 
def Gen_lucky(n):
    if(len(n)==1):
        if(n<"4"):
            return 0
        if(n<"7"):
            return 1
        return 2
    s=str(n)
    if(s[0]<'4'):
        return 0
    if(s[0]=='4'):
        return Gen_lucky(s[1:])
    if(s[0]<'7'):
        return 2**(len(s)-1)
    if(s[0]=='7'):
        return 2**(len(s)-1)+Gen_lucky(s[1:])
    else:
        return 2**len(s)
        
 
def Form(X,k):
    if(k==0):
        return X
    for i in range(len(X)):
        if(k>=F[len(X)-i-1]):
            h=k//F[len(X)-i-1]
            r=k%F[len(X)-i-1]
            G=list(X[i+1:])
            G.remove(X[i+h])
            G=[X[i]]+G
            return Form(X[:i]+[X[i+h]]+G,r)
 
p=1
 
F=[1]
i=1
while(p<=10**15):
    p*=i
    F.append(p)
    i+=1
 
n,k=map(int,input().split())
 
 
    
if(n<=14):
    if(k>F[n]):
        print(-1)
    else:
        L=Form(list(range(1,n+1)),k-1)
        x=0
        for i in range(n):
            if(lucky(i+1) and lucky(L[i])):
                x+=1
        print(x)
else:
    L=Form(list(range(n-14,n+1)),k-1)
    ss=str(n-15)
    x=0
    for i in range(1,len(ss)):
        x+=2**i
    x+=Gen_lucky(ss)
    for i in range(n-14,n+1):
        if(lucky(L[i-n+14]) and lucky(i)):
            x+=1
    print(x)