#include <stdio.h>

int main(void)
{
  float x;
  float money = 100;
  int year = 0;
  
  scanf("%f", &x);
  for(year = 0;; year++)
  {
    if(money >= x)
      break;
    year++;
    money *= 1.1;
  }
  
  printf("%d\n", year);
  return 0;
}