Easter Party

#include <iostream>
#include <iomanip>

using namespace std;

int main() {
    int guest;
    cin >> guest;

    double envelope, budget;
    cin >> envelope >> budget;

    double sum = guest * envelope;

    if (guest >= 10 && guest <= 15) {
        sum *= 0.85;
    }
    else if (guest > 15 && guest <= 20) {
        sum *= 0.80;
    }
    else if (guest > 20) {
        sum *= 0.75;
    }

    sum += budget / 10;

    if (budget >= sum) {
        cout << "It is party time! " << fixed << setprecision(2) << budget - sum << " leva left.\n";
    }
    else {
        cout << "No party! " << fixed << setprecision(2) << sum - budget << " leva needed.\n";
    }
    return 0;
}