#include <iostream>
#include <algorithm> // next_permutation
#include <iomanip>
#include <cmath>
#include <vector>
#include <sstream>
#include <string>
#include <cstdio>
#include <stack>
#include <queue>
#include <list>
#include <numeric> //accumulate
//#include <unordered_map> //???????????\??¢??°
#include <fstream> //ifstream, ofstream

#define NDEBUG //NDEBUG???#include <cassert>???????????????????????????????????´???assert?????????????????????????????????NDEBUG????????????????????¨
#include <cassert> //assert


using namespace std;

//???????????°??????TEST????????????????????¬???????????????????????????????????¢????????????
#define TEST //*******************************************************************************************************************************************
//?????????????????¨??§?????\????????????????????????????????°?????????????¨???????????????????dout???????????????????????§???????????¬??????????????????????????????????????????
//??????????????????????????????????????????????????????????§?CPU???????£??????????????????§???TLE?????????????????????????????????????????§????????¨???                           ????????????????????????cerr????????£????????????????????????????????????
#ifdef TEST
#define dout cout
#else
stringstream dummy; //???????????°??????dout?????????????????????????????????
#define dout dummy.str(""); dummy.clear(stringstream::goodbit); dummy //dummy?????????????????????????????????????????¨?????¢?????¢???????????????
//???????????¨??????????????????goodbit?????????????????????????????¨???????????´????????????????????????????????¨?????°?????????????????§???????????????????????????????????? http://d.hatena.ne.jp/linden/20060427/p1
#endif

//?¨??????????????????????????????????????????????????????´??????OUTPUT2TEXTFILE????????????????????¬???????????????????????????????????¢????????????
//#define OUTPUT2TEXTFILE //*******************************************************************************************************************************************
#ifdef OUTPUT2TEXTFILE
#define dout outputfile //??¨????????????TLE????????§?????????dout?????¨??¨??????????????¢????????????????????????????????????????????§????¨????????????´??????????????£??????????????????????¨?????????????????????????????????????????????§?????????????????????
//TEST??????????????????????????¨???outputfile??????????????????????????????
#define OUTPUTFILENAME "output.txt"
ofstream outputfile(OUTPUTFILENAME);
#define OutputFilePath "/Users/Nag/Documents/Prgm/Test/DerivedData/Test/Build/Products/Debug/output.txt"
#endif

#define disp(A) dout << #A << " = " << (A) << endl
#define disP(A) dout << setw(3) << (A) << " " // << setw(3) ??????????????\????????????
#define rep(i,a,n) for(int (i)=(a); (i)<(n); (i)++)

#define dispAll(A,n) dout << #A << " = "; rep(j, 0, (n)) {disP(A[j]);} dout << endl

typedef pair<int,int> pii;
typedef vector<int> vi;
typedef unsigned long long ll;

const int INF = 1e9-1;


int partition(int A[], int p, int r) { //A[p] ... A[r] ??¨????????°?????????????°??????????A[r]?????????????????¨?????????pivot??\??????pivot????????§????????????2????????°??????????????????????????????????????????pivot???index?????????
    int pivot = A[r];
    
    int i = p-1; //i?????§???pivot??\???????????????????¬????pivot??\?????????????????????????????£?????´??????i+1?????´????????????????????°??????
    int tmp;
    
    rep(j,p,r) {
        if( A[j] <= pivot ) {
            i++;
            
            //swap A[i] and A[j]
            tmp = A[i];
            A[i] = A[j];
            A[j] = tmp;
        }
    }
    
    //swap A[i+1] and pivot=A[r]
    tmp = A[i+1];
    A[i+1] = A[r];
    A[r] = tmp;

    return i+1; //i?????§???pivoit??\??????????????????i+1???pivot
}


int main(){
    
    int N; cin >> N;
    
    int a[N];
    rep(i,0,N) cin >> a[i];
    
//    dispAll(a,N);
    
    int indexOfPivot = partition(a,0,N-1);
    
    rep(i,0,N) {
        if(i!=0) cout << " ";
        
        if(i==indexOfPivot) cout << "[" << a[i] << "]";
        else cout << a[i];
    }
    cout << endl;
    
    
    
    
#ifdef OUTPUT2TEXTFILE
    outputfile.close();
    cout << "\"" << OutputFilePath << "\"" << endl;
#endif
    
    return 0;
}

Measured memory_bytes: 3464