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#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#define MAX 100000
#define ABIG 1
#define BBIG 0
 
int strBigger(char* a, char* b, int a_len, int b_len){
  // printf("comparing %s and %s\n", a, b);
  // return 1 if a > b; 0 if a < b
 
  if( a_len < b_len ){
    for(int i=0; i<a_len; i++){
      // printf("a[%d] = %c, b[%d] = %c\n", i, a[i], i, b[i]);
      if( a[i] == b[i] ){
        // printf("a[%d] == b[%d] = %c\n", i, i, b[i]);
        continue;
 
      }else if( a[i] > b[i] ){
        // printf("a[%d] = %c > b[%d] = %c\n", i, a[i], i, b[i]);
        return ABIG;
 
      }else if( a[i] < b[i] ){
        // printf("a[%d] = %c < b[%d] = %c\n", i, a[i], i, b[i]);
        return BBIG;
      }
    }
 
    // check if remaining of b is all smaller than last digit of a
    return strBigger(a, b+a_len, a_len, b_len - a_len);
 
 
  }else if( a_len > b_len ){
    for(int i=0; i<b_len; i++){
      // printf("a[%d] = %c, b[%d] = %c\n", i, a[i], i, b[i]);
      if( a[i] == b[i] ){
        // printf("a[%d] == b[%d] = %c\n", i, i, b[i]);
        continue;
 
      }else if( a[i] > b[i] ){
        // printf("a[%d] = %c > b[%d] = %c\n", i, a[i], i, b[i]);
        return ABIG;
 
      }else if( a[i] < b[i] ){
        // printf("a[%d] = %c < b[%d] = %c\n", i, a[i], i, b[i]);
        return BBIG;
      }
    }
 
    // check if remaining of b is all smaller than last digit of a
    return strBigger(a+b_len, b, a_len - b_len, b_len);
 
 
  }else if( a_len == b_len ){
    for(int i=0; i<b_len; i++){
      // printf("a[%d] = %c, b[%d] = %c\n", i, a[i], i, b[i]);
      if( a[i] == b[i] ){
        // printf("a[%d] == b[%d] = %c\n", i, i, b[i]);
        continue;
 
      }else if( a[i] > b[i] ){
        // printf("a[%d] = %c > b[%d] = %c\n", i, a[i], i, b[i]);
        return ABIG;
 
      }else if( a[i] < b[i] ){
        // printf("a[%d] = %c < b[%d] = %c\n", i, a[i], i, b[i]);
        return BBIG;
      }
    }
 
    return ABIG;
  }
 
}
 
int main(){
  int n; scanf("%d", &n);
  char nums[n][MAX];
 
  for(int i=0; i<n; i++){
    char str[MAX];
    scanf("%s", str);
    strncpy(nums[i], str, strlen(str));
    // printf("nums[%d] = %s\n", i, str);
  }
 
  // bubble sort nums small to big
  for(int i=0; i<n; i++){
    for(int j=0; j<n-i-1; j++){
      if( strBigger( nums[j], nums[j+1], strlen(nums[j]), strlen(nums[j+1]) ) ){
        // nums[j] > nums[j+1]
        // printf("%s is larger than %s\n", nums[j], nums[j+1]);
        char temp[MAX];
        strcpy(temp, nums[j]);
        strcpy(nums[j], nums[j+1]);
        strcpy(nums[j+1], temp);
      }
 
    }
  }
 
  for(int i=n-1; i>-1; i--){
    printf("%s", nums[i]);
  }
 
 
  return 0;
}
 
/*
100 10
  10010
  10100
-> 100 < 10
 
110 10
  11010
  10110
-> 110 > 10
 
100 11
  10011
  11100
-> 100 < 11
 
12 123
  12123
  12312
*/