function solve(input) {

    budgetOwned = Number(input.shift());
    nightsCount = Number(input.shift());
    nightPrice = Number(input.shift());
    spendPercentage = Number(input.shift());

    if (nightsCount > 7) {
        nightPrice = nightPrice - nightPrice * 0.05;
    } let nightSum = nightsCount * nightPrice
    let extraExpenses = budgetOwned * (spendPercentage / 100)
    let totalPrice = nightSum + extraExpenses

    if (budgetOwned > totalPrice) {
        let diff = totalPrice - budgetOwned;
        console.log(`Ivanovi will be left with ${Math.abs(diff.toFixed(2))} leva after vacation.`);
    } else {
        let diff = totalPrice - budgetOwned;
        console.log(`${Math.abs(diff.toFixed(2))} leva needed.`);

    }

}