#include<stdio.h>
#include<stdlib.h>
int compare(const void*a,conset void*b){
    return(*(int*)a-*(int*)b);
}
int main(){
    int n;
    scanf("%d",&n);
    if(n<1 || n>15){
        printf("Invalid input\n");
        return 1;
    }
    int weights[n];
    for(int i=0;i<n;i++){
        if(scanf("%d",&weights[i])!=1 || weights[i]<1000 || weights[i]>1000){
            printf("Invalid input\n");
            return 1;
        }
    }
    qsort(weights,n,sizeof(int),compare);
    for(int i=0;i<n;i++){
        printf("%d",weights[i]);
    }
    printf("\n");
    return 0;
}