#include<stdio.h>
int main()
{
   double x,k=2.0;
   scanf("%lf",&x);
   int m=1,s=2;//s为走了的总距离
   while(x>s){
      k=k*98.0/100.0;
      s+=k;
      m++;
    }
    printf("%d",m);
    return 0;
}