#include <iostream>
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#include <vector>
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​
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class Item
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{
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private:
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    int m_price{ 0 };
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    int m_amount{ 0 };
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public:
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    void set_price(int t_price)   { m_price = t_price; }
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    void set_amount(int t_amount) { m_amount = t_amount; }
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​
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    long tot_price() const { return m_amount * m_price; }
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};
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​
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int main()
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{
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    int a;
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    std::cin >> a;
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    std::vector<Item> items(a);
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​
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    for (int i = 0; i < a; i++)
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    {
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        int amount;
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        std::cin >> amount;
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        items[i].set_amount(amount);
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    }
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    for (int i = 0; i < a; i++)
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    {
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        int price;
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        std::cin >> price;
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        items[i].set_price(price);
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    }
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​
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    long sum{ 0 };
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    for (const auto& item : items)
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    {
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        sum += item.tot_price();
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    }
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​
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    std::cout << sum;
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}