# This code is generated by [Atcoder_base64](https://github.com/kyomukyomupurin/AtCoder_base64)
# Original source code : 

"""
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <chrono>
#include <cmath>
#include <complex>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <tuple>
#include <utility>
#include <vector>

using namespace std;

using int64 = long long;

#define all($) begin($), end($)
#define rall($) rbegin($), rend($)

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);

  const double pi = acos(-1);
  int r; cin >> r;
  cout << fixed << setprecision(17) << 2 * pi * r << endl;

  return 0;
}

"""

import base64
import subprocess


exe_bin = "e??420s#R400000000000{}h%0RR91pa}o~00000KmY&$00000s2czP0000000000Kma%Z2>?I<9RM5v1^@s61ONa4KmY&$00000KmY&$00000KmY&$00000_yGU_00000_yGU_000002mk;8000000{{R31ONa4I066w00000I066w00000I066w000008~^|S000008~^|S000000RR91000000RR911poj5000000000000000000000000000000s0;uA00000s0;uA00000001BW000000RR911^@s6Xbk`W00000Xbm6$00000Xbm6$00000r~&{0000007zF?T00000001BW000000ssI21^@s6fDHfu00000fDIr300000fDIr30000000IC20000000IC2000002mk;8000001ONa41ONa4R004100000R004100000R004100000L;wH)00000L;wH)000001ONa400000P~~)F1ONa4Knnl>00000Knnl>00000Knnl>00000L;wH)00000L;wH)000001ONa400000QRQ@G1^@s6000000000000000000000000000000000000000000000000005C8xG00000Qss1H1ONa4Xbk`W00000Xbm6$00000Xbm6$00000m;wL*00000m;wL*000000RR9100000FKlUIHZ(76WG!rIZgqGqcsMpKHZ(4CZ!R(b1ONa45C8xG0RR91M^04$000000{{R30ssI2000001ONa46aWAK0{{R3M^04$6k9*#jovqui~IAQb8z62vLDW)0ssI24gdfE0RR911^@s6000mI0RRL54gdfE000006qpP{bCw4J000000000000000000000000000000)c^nh5&!@I00000000000000000000K>+{&A^-pY00000000000000000000U;qFB5&!@I00000000000000000000RR9105&!@I00000000000000000000Gywnr5&!@I00000000000000000000BLM&a5&!@I00000000000000000000_W%F@5&!@I00000000000000000000n*aa+5&!@I000000000000000000009{>OVAOHXW00000000000000000000Pyqk{5&!@I000000000000000000005C8xGAOHXW00000000000000000000I{*LxAOHXW00000000000000000000y#N3J5&!@I000000000000000000004*>uG5datfKoB4R000005CH%H00000v;Y7A5datfU=bhy000007y$qP000000BmVub97{5D=RK@Z!R_fUtec!Z*E_6bYXIIUta)UNmNZ=WMy(?XK8bEWpY$aLu_wuWmI8eY-IpnNmNZ=a%E>}b97~LR82!{Z*FB&VPb4$0AE^8Q)zN@MN(-1Us_XiG-YmNY)NBNbTKhwXkl_+baG*7baP2#MMY9mbTKnxVRLC?UvG1Ca%Ev{NmO4{FkeMeHeUc=T251MIbTg*X>N06a&$>#MMY9mZ&Y6ZUs_XiGh=CP0AE^8Q*=0KZ*yN_VRL0PNp5L$L@`Bn0AE^8Q*=0KZ*yN_VRL0MHFJ4xV_$b^bZB35bYy97MPdM7T251RIB9QlUt(c%Wi&}{X>>y|MRovRT2pj1V{dhI0BmVuV=i-VE;ayPUvqR}V{2byXlq|)VQFjtUteQ*VP9c%Wq4_H0AF8Ycwt{=X>MU`X?kS<Uter#Vq;%(bYXIIUu|J&ZU9G2NkT(kGA=X#M@&gVLtip3GA=a$M@&gVLs(c}GcGhPIRHmYNkT(dSYI<PGynhq0ssR50ssO40{{d70ssX700093000000ssO40ssI2000000RRF3836zQ5C8xGFaQ7m6lrM<000C4VgUdE5C8xGbsA|200093YykiO000000RRF30RR915C8xG00000iGL{q000F5cmV(a5C8xGbSaVu00062h5-No00000Xbm6$000002mk;800000pb7v000000a19^;000002mk;800000a0vha00000cnu%`000002mk;800000U<v>L000002oN9u000002mk;8000002oN9u00000&<`L0000001^@s60ssI20000000000*bg88000001^@s62><{90000000000;13`G000001^@s63IG5A0000000000=no(O000001^@s63jhEB0000000000@DCsW000001^@s63;+NC0000000000_zxfe000001^@s64FCWD0000000000KoB4R000001poj54gdfE0000000000U=bhy000001poj54*&oF0000000000m=7QT000002LJ#70RR910000000000pbsDb000002LJ#70{{R30000000000s1G0j000002LJ#71ONa40000000000un!;r000002LJ#71poj50000000000xDOxz000002LJ#71^@s60000000000zz-k*000002LJ#72LJ#70000000000$PXX@000002LJ#72mk;80000000000NQ3MMNQ(u%2Ot1Qg}`(I|IkQ-#0bLx0000000000|20AfAOQa*L<b-M4<A4P|0O~PAOL6p0002#;Q#;s|0OyHAOL6q0002#(EtDc|0Oa9AOL6r0002#!2kdM|0OC1AOL6s0002#u>b%6|0N;^AOL6t0002#p#T5>|0Nm+AOL6u0002#kpKVx|0NO!AOL6v0002#fdBvh|0N0sAOL2N0000000000NQ3McG5=&piv%So0000;i9{p_F~I0$|Ns9;jdUagNR2&d2p|AR#|1_SAOHXW008J||Ns9;iv=<VAOJ{>Ju3$w0A>&Gz(|Ww=<*LLL?i_A4_O5b0ssI=0s4zV7)ZxL2oV4P044kW|Nn!?1c^cz=x6``|450)=nwz@|455WBnV_kGYlmt0001W2Qk1%gTxra=p+CC{|_GkNR2%L2_OJSgX{?CApigWNQ*sj1|R@PjTL$ZAOJ{>HRK2&07!$x2<hVf|Nmx?G3`l-(OyW2;z)z!@K97tjRk4}002mh4f6m107#8J4FCWC{}mPnAOQ3aA4C8ENR2%?1|R@cNR0(C1|R@PIrvD4<#ZWHiv{WhAOJ{(z;q2=|KMgW4<Cd800000UBeF_KmcYg4<Cd800000NR2)D1t0)OjWzNGAOKZJDgH=_<w(K)14xPRNWthoNCC!3(f)K8NQ(ur1t0)Og}`(SUH{-_4<Cd800000UBeF_KmcYg4<Cd800000fISfiAOHY$FGzzuUj-ll098nd<#Y^4i#>`3AOPq+{{R2zNdN!;#s%pIAOHbf!w(;T00000^TTEjA4C8ERY-~DUFl~3|NmwWA4C8EL03UmNr~4%RY6otjU}c6AOKZJjV-PMAOKTAiTz25_Dm_|NQ3MMNWuLB=s*4c|44=HbRaR?4<Cd800000Oo{qTiS|T^??L|*+(?7N0Z2LBb?Qii#0XnmL0myyL0&;$!;oe!4<Cd800000^TPlDNQ3MMNQ1-(!vFvP0RRF3000007%fCp`ym-X0UHB5L;wH)2LJ#70R8{}kN^Mxfc^jfxBvhEkp2Jv&;S4cF#iAl>;M1&VE+IAU;qFBaR2}R2mt^9;Q#;sPyqk{000006aWAK000000eVsZ0eBDr8w>{skO2n}6aWAK8~^|S`2GL?D*ylh00000000006aWAK000000eVsZ0eBDr8w>{skO2SyBme*a8~^|SX#D^GfB*mh01gmF4j4)g3wH>B06!W#Dl;S^000006aWAKL;wH)!2JLJ2mk;800000000007ytkOTmS$7xcvYBod5s;07MQT0+R|32tf+~7ytkOcmMzZJpKRwE&u=k080)KUJeKV00000L;wH)lmGw#VE+IAWdHyG074EBj{-st7>)x)4j_#LLJla51xOAsh6YFuID-dG4nT4aI6)3DK@KQF4j@7f7(xyZLJkN35C8xG+yDRoi2nco0ssI20000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000pb7v000000a0vha00000U<v>L000000RR91000000RR91000000RR9100000836zQ000003;+NC00000AP4{e000004FCWD00000Bntol0000082|tP00000Xbm6$000008vp<R000005C8xG000008UO$Q00000cnu%`000008~^|S000002mk;800000_5S~F00000m;wL*000001poj500000Km-5)000001^@s600000zybgO000003IG5A00000k^uk!000003jhEB000007ytkO000006#xJL0000000000000000{{R300000fDa%5000000ssI200000r~m)}000006aWAK000002LJ#7000007XSbN00000cn1Ig000002LJ#700000SOx$9000002mk;800000AOQdX000002><{9000007ytkO000009smFU000002mk;800000`~UxM000000RR9900000{{R1P00000_yqs}00000|NsAQ000000ssI200000@c;jB00000(ggqj00000`TzfK000001ONa4000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000fDIr30000000000000000000000000RtNw90000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exe_bin = base64.b85decode(exe_bin)

with open("./kyomu", 'wb') as f:
    f.write(exe_bin)

subprocess.run(["chmod +x ./kyomu"], shell=True)
subprocess.run(["./kyomu"], shell=True)

Measured memory_bytes: 10652