#include<stdio.h>
#include<math.h>
int main()
{
	int ar[50000000]={0},i,j,N=100000000,p=0,x,n,beg,mid,end,d;
	float a,b,c;

	for(int i=1;(i+i+1)*(i+i+1)<N;i++)
	{
		if(!ar[i])
		{

			j=(i+i+1)*(i+i+1)/2;
			for(;j<=N/2;j+=i+i+1)
			ar[j]=1;
		}

	}
        ar[p++]=2;
	for(int k=1;k<N/2;k++)
	{
		if(!ar[k])
		ar[p++]=k+k+1;
	}

	scanf("%d",&x);
	while(x)
	{
		beg=0;end=p;mid=0;
		while(beg<=end)
		{

			mid=(beg+end)/2;
			/*printf("beg=%d mid=%d end=%d\n",beg,mid,end);*/
			if(ar[mid]==x)
			break;
			else if(ar[mid]>x)
			end=mid-1;
			else
			beg=mid+1;
		}
		if(ar[mid]<=x)
		a=float(mid+1);
		else
		a=float(mid);

		b=a-x/log(x);
		if(b<0)
		b*=-1;
		c=(b)/a*100;
		printf("%0.1f\n",c);
		scanf("%d",&x);


	}



}