It's so hot

Classical Mechanics Level 4

Three objects of same heat capacity with temperature $T_1=200~\mbox{K}$ , $T_2=400~\mbox{K}$ and $T_3=400~\mbox{K}$ exchange heat with each other. They are isolated from the rest of the universe. Find the highest possible temperature one of them can reach in kelvin.

Hint: The first and second laws of thermodynamics are your friend.