// URL: https://yukicoder.me/problems/no/23 import std.algorithm, std.array, std.container, std.math, std.range, std.typecons, std.string; version(unittest) {} else void main() { int H, A, D; io.getV(H, A, D); auto r = cast(double)H; foreach (x; 0..(H+D-1)/D+1) { auto ed = x*cast(double)3/2; auto cd = H-D*x <= 0 ? 0 : (H-D*x+A-1)/A; r = min(r, ed+cd); } io.put(r); } auto io = IO!()(); import std.stdio; struct IO(string floatFormat = "%.10f", string delimiter = " ", alias IN = stdin, alias OUT = stdout) { import std.conv, std.format, std.meta, std.traits; alias assignable = hasAssignableElements; auto getV(T...)(ref T v) { foreach (ref w; v) get(w); } auto getA(T)(size_t n, ref T v) if (assignable!T) { v = new T(n); foreach (ref w; v) get(w); } auto getC(T...)(size_t n, ref T v) if (allSatisfy!(assignable, T)) { foreach (ref w; v) w = new typeof(w)(n); foreach (i; 0..n) foreach (ref w; v) get(w[i]); } auto getM(T)(size_t r, size_t c, ref T v) if (assignable!T && assignable!(ElementType!T)) { v = new T(r); foreach (ref w; v) getA(c, w); } auto put(bool flush = false, T...)(T v) { foreach (i, w; v) { putA(w); if (i < v.length-1) OUT.write(delimiter); } OUT.writeln; static if (flush) OUT.flush(); } auto putB(S, T)(bool c, S t, T f) { if (c) put(t); else put(f); } auto putRaw(T...)(T v) { OUT.write(v); OUT.writeln; } private { dchar[] buf; auto sp = (new dchar[](0)).splitter; void nextLine() { IN.readln(buf); sp = buf.splitter; } auto get(T)(ref T v) { if (sp.empty) nextLine(); v = sp.front.to!T; sp.popFront(); } auto putR(T)(T v) { auto w = v; while (!w.empty) { putA(w.front); w.popFront(); if (!w.empty) OUT.write(delimiter); } } auto putA(T)(T v) { static if (isInputRange!T && !isSomeString!T) putR(v); else if (isFloatingPoint!T) OUT.write(format(floatFormat, v)); else OUT.write(v); } } }