function blackFlag(input) {
    let days = Number(input.shift());
    let dailyPlunder = Number(input.shift());
    let targetPlunder = Number(input.shift());

    let totalPlunder = 0;
    for (let i = 1; i <= days; i++) {

        totalPlunder += dailyPlunder;
        if (i % 3 === 0) {

            totalPlunder += (dailyPlunder * 0.50);

        } else if (i % 5 === 0) {

            totalPlunder *= 0.70;
        }
    }
    if (totalPlunder >= targetPlunder) {
        console.log(`Ahoy! ${totalPlunder.toFixed(2)} plunder gained.`);

    } else {
        let percentage = ((totalPlunder * 100) / targetPlunder);
        console.log(`Collected only ${percentage.toFixed(2)}% of the plunder.`);

    }
}