import std.stdio, std.string, std.conv;
import std.array, std.algorithm, std.range;

void main()
{
    foreach(a;stdin.byLine().map!(to!real)())
    {
        auto t=a;
        foreach(i;2..11)
            a/=(i&1)?3:0.5,t+=a;
        writefln("%.7f",t);
    }
}