#include<stdio.h>
#include<stdlib.h>
int main(){
	    double eletric,money;
	scanf("%lf",&eletric);
 
    if(eletric<=150)	
        money=eletric*0.4463;//电量少于150KWh时的电费
    if(eletric>150&&eletric<=400)	
        money=150*0.4463+(eletric-150)*0.4663;//电量多于150KWh，少于400KWh时的电费
    if(eletric>400)		
        money=150*0.4463+250*0.4663+(eletric-400)*0.5663;//电量多于400KWh时的电费
    
    printf("%.1lf",money);//保留小数点1位
    printf("\n");//换行

	return 0;
}
/**************************************************************
	Problem: 1463
	User: admin
	Language: C
	Result: Accepted
	Time:25 ms
	Memory:1144 kb
****************************************************************/