include <stdio.h>

int main() {

double c;
int a;
scanf("%d", &a);
if (a <= 150) {
	c = a * 0.4463;
} else if (a > 150 && a <= 400) {
	c = ((150 * 0.4463) + ((a - 150) * 0.4663));
} else if (a > 400) {
	c = ((150 * 0.4463) + (250 * 0.4663) + ((a - 400) * 0.5663));
}
printf("%.1lf", c);
return 0;

}