#include <iostream>
#include <cmath>
#include <iomanip>

using namespace std;

int main()
{
	double x,coef,result=0,deg=0;
	cin >> x;
	while(1)
	{
		cin >> coef;
		if(cin.eof())
		{
			cout << setprecision(4) << fixed << result << endl;
			return 0;
		}
		result += coef*pow(x,deg++);
	}
}