#include <bits/stdc++.h>
using namespace std;
int main() {
  std::map<char, int> count;
  count.insert(std::pair<char, int>('A', 0));
  count.insert(std::pair<char, int>('B', 0));
  count.insert(std::pair<char, int>('C', 0));
  for (int k = 0; k < 3; k++) {
    std::string temp;
    getline(std::cin, temp);
    if (temp[1] == '<')
      count[temp[2]]++;
    else
      count[temp[0]]++;
  }
  if (count['A'] == 1 && count['B'] == 1 && count['C'] == 1)
    cout << "Impossible" << endl;
  else {
    if (count['A'] == 0)
      printf("A");
    else if (count['B'] == 0)
      printf("B");
    else if (count['C'] == 0)
      printf("C");
    if (count['A'] == 1)
      printf("A");
    else if (count['B'] == 1)
      printf("B");
    else if (count['C'] == 1)
      printf("C");
    if (count['A'] == 2)
      printf("A");
    else if (count['B'] == 2)
      printf("B");
    else if (count['C'] == 2)
      printf("C");
  }
  return 0;
}
