#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
ll pow2(int a)
{
    if(a)return 1<<a;
    return 1;
}
ll pow3(int a)
{
	if(a)return 1<<a;
	return 0;
}
ll f(string x)
{
    ll j;
    if(x=="0")return 1;
    if(x=="1")return 2;
    if(x[0]=='0')j=(1<<((int)x.length()))-2;
    else j=(1<<((int)x.length()-1))+(1<<((int)x.length()))-2;
    j++;
    reverse(x.begin(),x.end());
    int l=x.length()-1;
    for(int i=0;i<l;i++)
        if(x[i]=='1')j+=pow2(i);
    return j;
}


int main()
{
    char ch;
    string s="";
    while(cin>>ch)ch=='4' ? s+='0' : s+='1';
    cout<<f(s);
    return 0;
}