C :

#include<stdio.h>
int main()
{
	int x,y;
	while(scanf("%d",&x)!=EOF)
	{
		if(x<1)
			y=x;
		else if(x>=1&&x<10)
			y=2*x-1;
		else
			y=3*x-11;
		printf("%d\n",y);
	}
	return 0;
}

C++ :

#include<stdio.h>
int tab(int x)
{
	int y;
	if(x<1)
		y=x;
	else if(x<=1||x<10)
		     y=2*x-1;
    else
		y=3*x-11;
	return y;
}
int main()
{
	int x;
	scanf("%d",&x);
	printf("%d\n",tab(x));
	return 0;
}