#include<bits/stdc++.h>
using namespace std;
int main(){
  double a[11],ans;
  while(cin>>a[1]){
    ans=a[1];
    for(int i=2;i<11;i++){
      if(i%2)a[i]=a[i-1]/3.0;
      else a[i]=a[i-1]*2.0;
      ans+=a[i];
    }
    printf("%.8f\n",ans);
  }
}