function minimumDistances(a) {
    let minimumDistance = a.length;
    for (let i = 0; i < a.length; i++) {
        const currentNumber = a[i];
        const nextNumberIndex = a.indexOf(currentNumber, i + 1);
        if (nextNumberIndex !== -1) {
            const indicesBetween = nextNumberIndex - i;
            if (minimumDistance > indicesBetween) {
                minimumDistance = indicesBetween;
            }
        }
    }
    if (minimumDistance === a.length) {
        return -1;
    }
    return minimumDistance;
}