#include <stdio.h>

int main(void)
{
	int i = 0;
	long double s, m = 0, k = 2;
	scanf("%lf", &s);
	while (m < s) {
		m = m + k;
		k = k * 98 / 100  ;
		i++;
}
	printf("%d", i);
	return 0;
}