import std.stdio, std.string, std.conv;
import std.range, std.algorithm, std.array, std.typecons, std.container;
import std.math, std.numeric, core.bitop;


void main() {
    int n;
    scan(n);

    if (n < 6) {
        writeln(0);
        return;
    }

    real ans = 1;
    ans -= 6 * (5.0 / 6.0)^^n;
    ans += 15 * (4.0 / 6.0)^^n;
    ans -= 20 * (3.0 / 6.0)^^n;
    ans += 15 * (2.0 / 6.0)^^n;
    ans -= 6 * (1.0 / 6.0)^^n;

    writefln("%.12f", ans);
}





void scan(T...)(ref T args) {
    import std.stdio : readln;
    import std.algorithm : splitter;
    import std.conv : to;
    import std.range.primitives;

    auto line = readln().splitter();
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}



void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}