#include <iostream>
#include <vector>
#include <string>
using namespace std;
 int f(int i,int j)
  {
  	string str1=to_string(i);
  	string str2=to_string(j);
  	string res_str = str1+str2;
  	int r= stoi(res_str);
  	return r;
  }
int main() {
	// your code goes here
     int n;
     cin>>n;
	vector<int>arr(n);
	int i=0;
	while(i<n)
	 {
	 	cin>>arr[i];
	 	i++;
	 }
 
	 int sum=0;
	 for(int i=0;i<n;i++)
	  {
	  	for(int j=i+1;j<n;j++)
	  	sum+=f(arr[i],arr[j]);
	  }
	 cout<<sum;
	return 0;
}

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