#include<iostream> #include<string> using namespace std; int main() { string s; cin>>s; double w = 1, ans = 0; int pos = s.find('.'); for(int i = pos - 1; i >= 0; --i) { if(s[i] == '1') ans += w; w *= 2; } w = 0.5; for(int i = pos + 1; i < s.size(); ++i) { if(s[i] == '1') ans += w; w /= 2; } cout<<ans; return 0; }