Proton in Crossed Electric and Magnetic Fields

A proton is moving undeflected in a region of crossed electric and magnetic fields at a constant speed of 2 × 10⁵ ms^–1. When the electric field is switched off, the proton moves along a circular path of radius 2 cm. The magnitude of electric field is x × 10⁴ N/C. the value of x is _____.
Take the mass of the proton = 1.6 × 10^–27 kg.