Axis-Aligned Area

Interview

Time limit2sMemory limit1024 MB

Summary

Given four sorted stick lengths, find the largest area of an axis-aligned rectangle the sticks can enclose.

Level: Easy3 of 10
Topics: Math, Implementation
Solved: No attempts yet

Statement

Alex has four sticks with positive integer lengths $a_1$ , $a_2$ , $a_3$ , and $a_4$ ( $a_1 \le a_2 \le a_3 \le a_4$ ). She places each stick parallel to one of the two coordinate axes. Find the largest area that the sticks can enclose.

Input

Four positive integers $a_1$ , $a_2$ , $a_3$ , and $a_4$ are given, each on a separate line, in non-decreasing order ( $1 \le a_1 \le a_2 \le a_3 \le a_4 \le 100$ ).

Output

Print the maximum area that can be enclosed.

Hint

The figure below shows one optimal placement for the first sample. The enclosed area is shaded in gray.

Examples2

Example 1
Input
```
2
2
4
7
```
Expected output
```
8
```
Example 2
Input
```
10
10
10
10
```
Expected output
```
100
```