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 >= 200) { writeln(1); return; } auto dp = new double[][](n + 1, 6 + 1); fillAll(dp, 0); dp[0][0] = 1; foreach (i ; 0 .. n) { foreach (j ; 0 .. 7) { dp[i+1][j] += dp[i][j] * j / 6.0; if (j < 6) { dp[i+1][j+1] += dp[i][j] * (6 - j) / 6.0; } } } writefln("%.12f", dp[n][6]); } 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); } } }