arr = []
def solve(n, num, index):
if n <= num:
arr.append(n)
elif n > num:
return
solve((n * 10) + 4, num, index + 1)
solve((n * 10) + 7, num, index + 1)
a = int(input())
solve(0, a, 0)
print(len(arr)-1)
#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#include<math.h>
using namespace std;
int main()
{
long long l, i, x, sum, p;
string n;
while (cin >> n)
{
l = n.size(); sum = 0, x = 1;
for (i = l - 1; i >= 0; i--) {
if (n[i] == '7')
p = pow(2, x);
else
p = pow(2, x) - pow(2, x - 1);
x++;
sum += p;
}
cout << sum << endl;
}
return 0;
}145. Binary Tree Postorder Traversal | 94. Binary Tree Inorder Traversal |
101. Symmetric Tree | 77. Combinations |
46. Permutations | 226. Invert Binary Tree |
112. Path Sum | 1556A - A Variety of Operations |
136. Single Number | 169. Majority Element |
119. Pascal's Triangle II | 409. Longest Palindrome |
1574A - Regular Bracket Sequences | 1574B - Combinatorics Homework |
1567A - Domino Disaster | 1593A - Elections |
1607A - Linear Keyboard | EQUALCOIN Equal Coins |
XOREQN Xor Equation | MAKEPAL Weird Palindrome Making |
HILLSEQ Hill Sequence | MAXBRIDGE Maximise the bridges |
WLDRPL Wildcard Replacement | 1221. Split a String in Balanced Strings |
1002. Find Common Characters | 1602A - Two Subsequences |
1555A - PizzaForces | 1607B - Odd Grasshopper |
1084A - The Fair Nut and Elevator | 1440B - Sum of Medians |