covert MET2

#include <bits/stdc++.h>
using namespace std;

int convertToB10(const char s[])
{
    int ans = 0;
    for (int i = 0; s[i]; i++)
        ans = ans * 2 + s[i] - '0';
    return ans;
}

int main()
{
    string s;
    cin >> s;
    cerr << convertToB10(s.c_str());
    return 0;
}