07. Fruit Shop

#include <iostream>
#include <string>
#include <iomanip>

using namespace std;

int main()
{

    double quantity;
    string day, fruits;

    cin >> fruits >> day >> quantity;

    bool is_it_incorrect_day = "Monday" || "Tuesday" || "Wednesday" || "Thursday" || "Friday" || "Saturday" || "Sunday";
    bool is_it_incorrect_fruit = "banana" || "apple" || "orange" || "grapefruit" || "kiwi" || "pineapple" || "grapes";

    if (day == "Monday" || day == "Tuesday" || day == "Wednesday" || day == "Thursday" || day == "Friday")
    {
        if (fruits == "banana") cout << fixed << setprecision(2) << 2.5 * quantity << endl;
        else if (fruits == "apple") cout << fixed << setprecision(2) << 1.2 * quantity << endl;
        else if (fruits == "orange") cout << fixed << setprecision(2) << 0.85 * quantity << endl;
        else if (fruits == "grapefruit") cout << fixed << setprecision(2) << 1.45 * quantity << endl;
        else if (fruits == "kiwi") cout << fixed << setprecision(2) << 2.7 * quantity << endl;
        else if (fruits == "pineapple") cout << fixed << setprecision(2) << 5.5 * quantity << endl;
        else if (fruits == "grapes") cout << fixed << setprecision(2) << 3.85 * quantity << endl;
        else cout << "error" << endl;
    }

    else if (day == "Saturday" || day == "Sunday")
    {
        if (fruits == "banana") cout << fixed << setprecision(2) << 2.7 * quantity << endl;
        else if (fruits == "apple") cout << fixed << setprecision(2) << 1.25 * quantity << endl;
        else if (fruits == "orange") cout << fixed << setprecision(2) << 0.90 * quantity << endl;
        else if (fruits == "grapefruit") cout << fixed << setprecision(2) << 1.60 * quantity << endl;
        else if (fruits == "kiwi") cout << fixed << setprecision(2) << 3.0 * quantity << endl;
        else if (fruits == "pineapple") cout << fixed << setprecision(2) << 5.6 * quantity << endl;
        else if (fruits == "grapes") cout << fixed << setprecision(2) << 4.2 * quantity << endl;
        else cout << "error" << endl;
    }

    else if (is_it_incorrect_day || is_it_incorrect_fruit)
    {
        cout << "error" << endl;
    }

    return 0;
}