#include <bits/stdc++.h>
using namespace std;
int main(){
	int a,b;
	float c;
	cin>>a>>b;
	if(b==1){
		c=a+(a*0.0325)*b;
	}else if(b==2){
		c=a+(a*0.0375)*b;
	}else if(b==3||b==4){
		c=a+(a*0.0425)*b;
	}else if(b>=5){
		c=a+(a*0.0475)*b;
	}
	printf("%.1f",c);
}
/**************************************************************
	Problem: 1341
	User: toughuatao1
	Language: C++
	Result: Accepted
	Time:34 ms
	Memory:2076 kb
****************************************************************/