百练 2933 停车场收费

# include <stdio.h>
int main()
{
	float t,sum;
	while(scanf("%f",&t)!=EOF)
	{
	if(t>24)
		break;
	sum=0;
	if(t<=3.0)
		sum=5;
	else
		sum=5+(t-3)*2;
	if(sum>40)
		sum=40;
	printf("%.2f\n",sum);
	}
	return 0;
}