#include<stdio.h>
#include<math.h>
int main()
{
	float s,n;
	scanf("%f",&s);
	n=log(1-0.01*s)/log(0.98);
	int N=n/1;
	int m=n+1;
	if(N==n)
	  printf("%d",n);
	else
	  printf("%d",m);
	return 0;
}