include

using namespace std;

int main() {

int n;
cin >> n;
double a, b, c ;
if (n <= 150) {
	a = n * 0.4463;
	printf("%.1lf", a);
}
if (n >= 151 && n <= 400) {
	b = (n - 150) * 0.4663 + 150 * 0.4463;
	printf("%.1lf", b);
}
if (n >= 401) {
	c = 150 * 0.4463 + 250 * 0.4663 + (n - 400) * 0.5663;
	printf("%.1lf", c);
}

return 0;

}