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
    let diff = budgetOwned - totalPrice

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

    }

}