#include <iostream>
#include <string.h>
#include <cstdio>
#include <algorithm>
#include <string>
#include <iomanip>
#include <math.h>
#include <map>
#include <set>
#include <cstdlib>
#include <vector>

typedef long long LL;
typedef unsigned long long ULL;
const int N = 1e5 + 10;
const int INF = 0x3f3f3f3f;
using namespace std;

int main()
{
	int n;
	double s;
	cin >> n >> s;
	if(n >= 5 && n < 10) s *= 0.9;
	if(n >= 10)s *= 0.8;
	printf("%.2lf", s * 1.0 * n);
	return 0;
}