Array Partition

Execution time limit is 1 second

Runtime memory usage limit is 128 megabytes

Given an integer array of $2 n$ integers.

Group these integers into $n$ pairs $(a_{1}, b_{1}), (a_{2}, b_{2}), ..., (a_{n}, b_{n})$ such that the sum of $min (a_{i}, b_{i})$ for all $i$ is maximized.

Input

The first line contains one number $n (n \leq 1 0^{5})$ . The second line contains $2 n$ integers, each no more than $1 0^{5}$ by absolute value.

Output

Print the maximum possible value of the sum.

i = 1 \sum n min (a_{i}, b_{i})

Examples

Input #1

Answer #1

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