Game exam

function solve(input) {
    let numbers = input.map(Number);
    let neededExperience = Number(numbers[0]);
    let count = Number(numbers[1]);
    let sum1 = 0;
    let battle = 0;
    let flag = false;
    for (let i = 2; i < numbers.length; i++) {
        battle++;
        let experiencePerBattle = Number(numbers[i]);
        if (battle % 3 === 0) {
            sum1 += experiencePerBattle + (experiencePerBattle * 0.15);
        } else if (battle % 15 === 0) {
            sum1 += experiencePerBattle + (experiencePerBattle * 0.05);
        }
        if (battle % 5 === 0) {
            sum1 = sum1 + (experiencePerBattle - (experiencePerBattle * 0.10));
        } else {
            sum1 += experiencePerBattle;
        }
        if (neededExperience <= sum1) {
            flag = true;
            battle --;
        }
    }
    if(flag === false){
        let rr = neededExperience - sum1;
        console.log(`Player was not able to collect the needed experience, ${rr.toFixed(2)} more needed.`)
    }else{
        console.log(`Player successfully collected his needed experience for ${battle + 1} battles.`);
    }
}