#include<bits/stdc++.h> using namespace std; int main() { double x,n,i,q=0,k=0; cin>>x>>n; k=i-1+sqrt(i+x); q=k; for(i=1;i<=n;i++){ q=i-1+sqrt(q); } printf("%.2f",sqrt(n+sqrt(q))); return 0; }