include <stdio.h>

int main() {

int n;
double w;
scanf("%d", &n);
if (n <= 150) {
	w = n * 0.4463;
	printf("%.1f", w);
} else if (n >= 151 && n <= 400) {
	w = 150 * 0.4463 + (n - 150) * 0.4663;
	printf("%.1f", w);
} else if (n >= 401 && n <= 10000) {
	w = (150 * 0.4463 ) + (400 - 150) * 0.4663 + (n - 400) * 0.5663;
	printf("%.1f", w);
}
return 0;

}