Pairs

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Time limit1sMemory limit1024 MB

Summary

Split four given integers into two pairs and print the largest possible sum of the two pair products.

Problem

Four numbers $a$ , $b$ , $c$ , and $d$ are given. Split them into two pairs so that the sum of the products within the pairs is maximal.

For example, if the numbers are 2, 3, 4, and 5, the best split is $(2, 3)$ and $(4, 5)$ . The sum is $2 \times 3 + 4 \times 5 = 26$ .

Four numbers $a$ , $b$ , $c$ , and $d$ are given. The absolute value of each number does not exceed 1000.

Print the maximum sum.