#include<iostream>
using namespace std;
int main() { //CL6 绩效奖金
	int n,k;
	cin>>n>>k;
	switch(k){
		case 5:cout<<n*0.1;break;
		case 4:cout<<n*0.08;break;
		case 3:cout<<n*0.06;break;
		case 2:cout<<n*0.04;break;
		default:cout<<0;
	}
	return 0;
}