def knapsack_recursive(weights, values, capacity, n):
    if n == 0 or capacity == 0:
        return 0
    if weights[n - 1] > capacity:
        return knapsack_recursive(weights, values, capacity, n - 1)
    exclude = knapsack_recursive(weights, values, capacity, n - 1)
    include = values[n - 1] + knapsack_recursive(
        weights, values, capacity - weights[n - 1], n - 1
    )
    return max(include, exclude)

weights = [2, 3, 4, 5]
values = [3, 4, 5, 6]
print(knapsack_recursive(weights, values, 5, len(weights)))  # 7