#include int main() { char in[14]; int count[13] = {0}; int twocount = 0; std::cin >> in; for(int i = 0; i < 13; i++) { count[in[i] - 'a']++; if(count[in[i] - 'a'] == 2) { twocount++; } if((count[in[i] - 'a'] >= 3) || (twocount >= 2)) { std::cout << "Impossible" << std::endl; return 0; } } if(twocount == 0) { std::cout << "a\nb\bc\nd\ne\nf\ng\nh\ni\nj\nk\nl\nm";// << std::endl; } else { for(int i = 0; i < 13; i++) { if(count[in[i] - 'a'] == 0) { std::cout << (char)(i + 'a');// << std::endl; } } } return 0; }