#include <stdio.h>
int show(float s)
{
	float j=2.0;
	int cut = 1;
	while (j < s)
	{
		j += float(j * 0.98);
		cut++;
	}
	return cut;
}

void print_show()
{
	float s;
	scanf("%f", &s);
	printf("%d",show(s));

}
int main()
{
	print_show();
	return 0;
}