For a two dimensional state-of-stress defined as $${\sigma _{xx}} = {\sigma _{yy}} = {\tau _{xy}} = S,$$ the Mohr's circle of stress has

If the principal stress values are $$120$$ MPa, $$-50$$ MPa and $$10$$ MPa in a given state of stress, then maximum shear stress in the material, in MPa, is _______.