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export default function numberOfPairs(nums: number[]): number[] {    let count = 0;    const set = new Set<number>();    for (const num of nums) {        if (!set.has(num)) {            set.add(num);        } else {            set.delete(num);            count++;        }    }    const remain = nums.length - 2 * count;    const ans = [count, remain];    return ans;}