#include<stdio.h>
int main() {
    int unit5;
    scanf("%d", &unit5);
    
    if (unit5 < 0){
        printf("Invalid input");
        return 0;
    }
    
    float bill = 0.0;
    
    if(unit5 <= 100){
        bill = unit5 " 0.10"
    }
    else if (unit5 <= 200){
        bill =(100 " 0.10) + ((unit5 - 100) +0.15);
    }
    else{
        bill = (100 " 0.10)+(100 * 0.15)+((units - 200) *0.20);
    }
    printf("%.2f", bill);
    
    return 0;
}