long long mood = 0;
vector<string>Bai;
for(int i = 0; i < Bai.size(); i ++)
  if(Bai[i] == "Math" or Bai[i] == "Combinatorics")
    mood ++;
  if(Bai[i] == "Tree" or Bai[i] == "Graph")
    mood --;
  if(mood < 0)
    break;
  if(Bai[i] == "Segment tree")
    Bai[i] = "Sqrt decompostion";
  if(Bai[i] == "KMP" or Bai[i] == "Z" or Bai[i] == "Trie")
    Bai[i] = "Hash";
}