C++ :

#include <bits/stdc++.h>
using namespace std;
bool compare(int a,int b){
	return a > b;
}

int main(){
	int r[4010],i,n,k = 0,x;
	cin>>n;
	for(i = 0;i < n;i++){
		cin>>x;
		while(x != 0){
			r[k] = x % 10;
			x = x / 10;
			k++;
		}
	}	
	
	sort(r,r+k,compare);
	for(i = 0;i < k;i++){
		cout<<r[i];
	}
	
}

Java :

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int num1 = scanner.nextInt();
//        int num2 = scanner.nextInt();
//        int num3 = scanner.nextInt();
        int[] a = new int[num1];
        int[] b = new int[100];
        double avg,x = 0;
        long s = 0;
        int count = 0;
        for (int i = 0; i < num1; i++) {
            a[i] = scanner.nextInt();
        }
        for (int i = 0; i < num1; i++) {
            while(true){
                b[count] = qiuYu(a[i]);
                a[i] /= 10;
                count++;
                if(a[i] == 0)break;
            }
        }
        int temp;
        for(int i = 0;i < count - 1;i++){
            for(int k = 0;k < count - i - 1;k++){
                if(b[k] > b[k + 1]){
                    temp = b[k];
                    b[k] = b[k + 1];
                    b[k + 1] = temp;
                }
            }
        }
        for (int i = count - 1; i >= 0; i--) {
            System.out.print(b[i]);
        }

    }

    public static boolean judge(int i,int j){
        int a,s = 0;
        while(i != 0){
            a = i % 10;
            s = s + a;
            i /= 10;
        }
        if(s == j)return true;
        else return false;
    }

    public static void paiXu(int[] a){
        int temp;
        for(int i = 0;i < a.length - 1;i++){
            for(int k = 0;k < a.length - i - 1;k++){
                if(a[k] > a[k + 1]){
                    temp = a[k];
                    a[k] = a[k + 1];
                    a[k + 1] = temp;
                }
            }
        }
    }

    public static int MAX(int[] a){
        int max = a[0];
        for (int i = 0; i < a.length; i++) {
            if(max < a[i]){
                max = a[i];
            }
        }
        return max;
    }

    public static int MIN(int[] a){
        int min = a[0];
        for (int i = 0; i < a.length; i++) {
            if(min > a[i]){
               min = a[i];
            }
        }
        return min;
    }
    public static int sum(int a){
        int x,s = 0;
        while(a != 0){
            x = a % 10;
            s = s + x;
            a /= 10;
        }
        return s;
    }
    public static boolean isPrime(int a){
        if(a <= 1)return false;
        else
        for(int i = 2;i <= Math.sqrt(a);i++){
            if(a % i == 0)return false;
        }return true;
    }

    public static int qiuYu(int i){
        int a;
        a = i % 10;
        return a;
    }
}

Python :

n=int(input())
a=input().split()
a=list(map(int,a))
b=[]
for i in a:
    k=len(str(i))
    for j in range(k):
        m=int(str(i)[j:j+1])
        b.append(m)
b=sorted(b)
b.reverse()
s=0
for i in range(0,len(b)):
    s=s*10+b[i]
print(s)