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def count_subset_pairs(collection):
    total = sum(collection)
    if total % 2 != 0:
        return 0
    
    n = len(collection)
    mid = n // 2
    left = collection[:mid]
    right = collection[mid:]
    
    from collections import defaultdict
    left_counts = defaultdict(int)
    for subset in generate_subsets(left):
        left_counts[sum(subset)] += 1
    
    right_counts = defaultdict(int)
    for subset in generate_subsets(right):
        right_counts[sum(subset)] += 1
    
    target = total // 2
    count = 0
    for s in left_counts:
        if (target - s) in right_counts:
            count += left_counts[s] * right_counts[target - s]
    
    return count
def generate_subsets(arr):
    n = len(arr)
    subsets = []
    for i in range(1, 1 << n):
        subset = []
        for j in range(n):
            if (i >> j) & 1:
                subset.append(arr[j])
        subsets.append(subset)
    return subsets
# ????
test_collection = [1, 2, 3, 4, 5, 6]
print(count_subset_pairs(test_collection))

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