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