;-)

function counterStrike(input) {
    let energy = Number(input.shift());
    let distance = input.shift();
    let gamesWon = 0;

    while (distance != "End of battle") {
        // if (Number.isNaN(energy)) {
        //     energy = 0;
        // }

        let numDistance = Number(distance);

        // The energy you need for reaching an enemy is equal to the distance you receive. 
        // Each time you reach an enemy, you win a battle, and your energy is reduced. 
        if (energy >= numDistance) {
            gamesWon++;
            energy -= numDistance;
        } else {
            // if (energy <= -1) {
            // }
            // energy = 0;

            // Otherwise, if you don't have enough energy to reach an enemy, end the program and print: 
            // "Not enough energy! Game ends with {count} won battles and {energy} energy".
            console.log(`Not enough energy! Game ends with ${gamesWon} won battles and ${energy} energy`);
            // subtract from energy in order to avoid printing win message below
            energy -= numDistance;
            break;
        }

        if (gamesWon % 3 === 0) {
            energy += gamesWon;
        }

        distance = input.shift();
    }

    // if (distance === "End of battle") {
    if (energy >= 0) {
        console.log(`Won battles: ${gamesWon}. Energy left: ${energy}`);
    }
}