#include<fstream>

using namespace std;

ifstream fin("1.in");
ofstream fout("1.out");

int main()
{
    int v[100],n,s1,s2,x,i,j;
    
    fin>>n;
    for(i=0;i<n;i++) fin>>v[i];
    
    for(i=0;i<n;i++)
       for(j=i+1;j<n;j++)
          {
              s1=0;
              x=v[i];
              while(x>0)
                        {
                          s1=s1+x%10;
                          x=x/10;
                         }
              s2=0;
              x=v[j];
              while(x>0)
                        {
                          s2=s2+x%10;
                          x=x/10;
                         }
              if(s1==s2) fout<<v[i]<<" "<<v[j]<<endl;
          }
       
       fin.close();
       fout.close();
       return 0;
}