#include<bits/stdc++.h>
using namespace std;
double x,n,s=1,y=1;
int main(){
	cin>>x>>n;
	for(int i=1;i<=n;i++){
		y*=x;
		s+=y;
	}
	cout<<fixed<<setprecision(2)<<s<<endl;
	return 0;
}

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

int main(){ double x,s=1,s1=1; int n; cin>>x>>n; for(int i=1;i<=n;i++){ s=s*x; s1+=s; } printf("%.2f",s1); }

//这题比较难，我想了4分钟
#include <bits/stdc++.h>
using namespace std;
int n;
double x,xn=1,sum=1;
signed main(){
	cin>>x>>n;
	for(int i=1;i<=n;i++) xn=xn*x,sum+=xn;
	cout<<fixed<<setprecision(2)<<sum<<" ";
	return 0;
}
//自己体会一遍再交吧