#include<bits/stdc++.h> using namespace std; int main(){ int n,x; cin>>x>>n; int cnt = x; for(int i=2;i<=n;i++){ int sum = 1; for(int j=1;j<=i;j++){ sum*=x; } if(i%2==0){ cnt-=sum; }else cnt+=sum; } cout<<fixed<<setprecision(2)<<cnt*1.0<<endl; return 0; }