Tallest Billboard

You are installing a billboard and want it to have the largest height possible. The billboard will have two steel supports, both of the same height. There are a collection of rods which can be welded together. For example, if you have rods of lengths 1, 2, and 3, you can weld them into one piece of length 6.

Return the largest possible height of your billboard installation. If you cannot support the billboard, return 0.

Examples
Input: [1,2,3,6]
Output: 6
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Tallest Billboard

You are installing a billboard and want it to have the largest height possible. The billboard will have two steel supports, both of the same height. There are a collection of `rods` which can be welded together. For example, if you have rods of lengths 1, 2, and 3, you can weld them into one piece of length 6.