TASKB

#include <bits/stdc++.h>
#define endl "\n"
using namespace std;
using ll = long long;


constexpr int N = 1e5+5;


map<string, int> mp;
int pm[N];
void Solve()
{
  int n, all = 0, m1=0, m2=0;
  string s1, s2;
  cin >> n;
  while(n--)
  {
    cin >> s1 >> s2;
    mp[s1]++;
    mp[s2]++;
  }
  for (auto [el, num]:mp)
  {
    pm[num]++;
    all++;
    if (num>m1)
    {
      m2=m1;
      s2=s1;
      m1=num;
      s1=el;
    }
    else if (num>m2)
    {
      m2=num;
      s2=el;
    }
  }
  int i = 1;
  for (; all>2; i++)
  {
    if (pm[i]!=all/2)
    {
      cout << "NO SOLUTION";
      return;
    }
    all-=pm[i];
  }
  i++;
  while(i<N)
  {
    if (pm[i]!=0)
    {
      cout << "NO SOLUTION";
      return;
    }
    i++;
  }
  cout << s1 <<" "<<  s2;
}

int main()
{

  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  Solve();
  return 0;
}