11780

#include <iostream>
#include <math.h>
#include <map>
#include <stdio.h>
#include <string>
#include <vector>

using namespace std;

map<int,int> mp;
int fib[50];
double dp[1010];

int main()
{
fib[0]=0;
fib[1]=1;
fib[2]=2;

mp[1]=1;
mp[2]=2;

for(int i=3;i<=20;i++)
{
fib[i]=fib[i-1]+fib[i-2];
mp[fib[i]]=i;
}
dp[1]=.4;
for(int i=1;i<=1000;i++)
{
double p=i*1.6;
double d=1000000;
for(int j=1;j<=18;j++)
{
if(i-fib[j]>=0)
{
int a=mp[fib[j]];
double x;
if((fib[a+1]+dp[i-fib[j]]-p)<0)
{
x=-1*(fib[a+1]+dp[i-fib[j]]-p);
}
else
x=(fib[a+1]+dp[i-fib[j]]-p);
if(x<d)
{
d=x;
dp[i]=fib[a+1]+dp[i-fib[j]];
}
}
}
}
int n;
while(cin>>n)
{
if(n==0)
break;

printf("%.2lf\n",fabs(dp[n]-n*1.6));//"\n";
}

return 0;
}