#include <stdio.h>
#include<string.h>
int atoi(char[]);
int main()
{
    char str[20][20],temp[20][20];
    int n,i,j,a;
    scanf("%d",&n);
    for(i=0;i<n;i++)
    {
        scanf("%s",str[i]);
    }
    for(i=0;i<n;i++)
    {
        for(j=0;j<n-1;j++)
        {
            a=atoi(str[j])-atoi(str[j+1]);
            if(a<0)
            {
                strcpy(temp[j],str[j]);
                strcpy(str[j],str[j+1]);
                strcpy(str[j+1],temp[j]);
            }
        }
    }
    for(i=0;i<n;i++)
    {
        printf("%s",str[i]);
    }
    return 0;
}

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