1.3. What is the maximum number of parts that 100 rays can divide a plane into?

## Second Round
### 1.3. Answer: 4951.

100 lines divide the plane into $100 \cdot 101 / 2 + 1$ parts. A ray is obtained from a line by destroying half of it. In this process, at least 2 parts are glued together, and if one system of rays contains another system of rays, the number of parts in the partition is no less. It remains to note that if only sufficiently distant rays are removed, the gluing will occur only along 100 pairs of parts.

## Second Round