Periodic table

The students of 3.a, Gimnazija Vič, Slovenia (2008/2009) were playing a special game during chemistry lession. For example, they wrote the word "water" as "WAtEr", as list of the following symbols for elements: Tungsten (W), Astatine (At) and Erbium (Er).

This game is representing such fun for them, so they are asking you to write a program to simplify their task. They contributed everything they could and wrote you the whole list of elements.

List of elements:
"H", "He", "Li", "Be", "B", "C", "N", "O", "F", "Ne", "Na", "Mg", "Al", "Si", "P", "S", "Cl", "Ar", "K", "Ca", "Sc", "Ti", "V", "Cr", "Mn", "Fe", "Co", "Ni", "Cu", "Zn", "Ga", "Ge", "As", "Se", "Br", "Kr", "Rb", "Sr", "Y", "Zr", "Nb", "Mo", "Tc", "Ru", "Rh", "Pd", "Ag", "Cd", "In", "Sn", "Sb", "Te", "I", "Xe", "Cs", "Ba", "La", "Ce", "Pr", "Nd", "Pm", "Sm", "Eu", "Gd", "Tb", "Dy", "Ho", "Er", "Tm", "Yb", "Lu", "Hf", "Ta", "W", "Re", "Os", "Ir", "Pt", "Au", "Hg", "Tl", "Pb", "Bi", "Po", "At", "Rn", "Fr", "Ra", "Ac", "Th", "Pa", "U", "Np", "Pu", "Am", "Cm", "Bk", "Cf", "Es", "Fm", "Md", "No", "Lr", "Rf", "Db", "Sg", "Bh", "Hs", "Mt", "Ds", "Rg"

In case there are multiple possible solutions for the same word, output the one that contains the most elements. This could, for example happen when you have "co" in a word. It could be written as "Co" (Cobalt) or "CO" (Carbon and Oxygen). Output "CO" in such cases!