#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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