#include <bits/stdc++.h>
using namespace std;
#define Foreach(i, c) for(__typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define For(i,a,b) for(int (i)=(a);(i) < (b); ++(i))
#define rof(i,a,b) for(int (i)=(a);(i) > (b); --(i))
#define rep(i, c)  for(auto &(i) : (c))
#define x     first
#define y     second
#define pb  push_back
#define PB  pop_back()
#define iOS  ios_base::sync_with_stdio(false)
#define sqr(a)  (((a) * (a)))
#define all(a)  a.begin() , a.end()
#define error(x) cerr << #x << " = " << (x) <<endl
#define Error(a,b) cerr<<"( "<<#a<<" , "<<#b<<" ) = ( "<<(a)<<" , "<<(b)<<" )\n";
#define errop(a) cerr<<#a<<" = ( "<<((a).x)<<" , "<<((a).y)<<" )\n";
#define coud(a,b) cout<<fixed << setprecision((b)) << (a)
#define L(x)  ((x)<<1)
#define R(x)  (((x)<<1)+1)
#define umap  unordered_map
//#define max(x,y)  ((x) > (y) ? (x) : (y))
#define double long double
typedef long long ll;
typedef pair<int,int>pii;
typedef vector<int> vi;
typedef complex<double> point;
inline ll binary(string n){
	ll ans = 0LL;
	For(i,0,n.size())
		ans  = (2LL*ans + (ll)(n[i]-'0'));
	ll p = 1LL;
	For(i,0,n.size())
		p = (p << 1);
	ans += p-1LL;
	return ans;
}
inline string lu(string s){
	For(i,0,s.size())
		s[i] = (char)(s[i]=='4'?'0':'1');
	return s;
}
int main(){
	iOS;
	string n;
	cin >> n;
	cout << binary(lu(n)) << endl;
}