#include <iostream>
#include <cstdio>

using namespace std;

int main()
{
	int n;
	double x;
	double sum = 1; //ʼΪ1 
	double r = 1;
	cin >> x >> n;
	while(n--) //nѯ 
	{
		r *= x;
		sum += r;
	}
	printf("%.2f\n", sum);
	return 0;
}