ITP exceptions 1 second

#include <iostream>

using namespace std;

class LengthsNotEqualException : exception {
public:
    LengthsNotEqualException() {
    }

    const char* what() const noexcept {
        return "The lengths of two containers are not equal";
    }
};

class Container {
private:
    int lenght;
    int* arr;

public:
    Container() {
        cin >> lenght;
        arr = new int[lenght];
        for (int i = 0; i < lenght; i++)
            cin >> arr[i];
    }

    friend int dot_product(Container& a, Container& b) {
        if (a.lenght != b.lenght)
            throw LengthsNotEqualException();

        int c = 0;
        for (int i = 0; i < a.lenght; i++)
            c += a.arr[i] * b.arr[i];
        return c;
    }
};

int main()
{
    Container a, b;

    try {
        cout << dot_product(a, b);
    }
    catch (LengthsNotEqualException & exception){
        cout << exception.what();
    }
    catch (exception & exception) {
        cout << exception.what();
    }
}