cake

function cake(input) {
    let height = Number(input.shift());
    let width = Number(input.shift());
    let cakeSize = height * width;
    let neededPieces = 0;
    while (neededPieces < cakeSize) {

        let pieces = input.shift();

        if (pieces != "STOP") {
            neededPieces += Number(pieces);
            if (neededPieces >= cakeSize) {
                console.log(`No more cake left! You need ${neededPieces - cakeSize} pieces more.`);
            }
        } else {
            console.log(`${cakeSize - neededPieces} pieces are left.`);
        }
    }
}

cake([10, 10, 20, 20, 20, 20, 21]);
cake([10, 2, 2, 4, 6, "STOP"]);