1055

# include <stdio.h>
main()
{
	float x,y;
	scanf("%f",&x);
	if(x<1)
	{
		y=x;
	}
	else if(x>=1&&x<10)
	{
		y=2*x-1;
	}
	else if(x>=10)
	{
		y=3*x-11;
	}
	printf("%.2f",y);
}