#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
double money = 0;
double total = 0;
int year = 0;
scanf("%lf", &money);
total = money;
while (total < money * 2)
{
year++;
total = total*1.05;
}
printf("%d\n", year);
return 0;
}