As usual, we denote z = x + iy with real-valued coordinates x and y. For which values of x and y does the function e2.1. take purely imaginary values? The coordinate (choose x or y) x ory is arbitrary, and the coordinate (choose x or y) x ory is given in the form a + 8k with some positive a, B and an arbitrary integer k. The smallest possible value of a is and the value of B is