TP = 0.0
    FP = 0.0
    FN = 0.0
    TN = 0.0

    N = len(clusters)

    for i in range(N):
        for j in range(N):
            if i == j:
                continue

            if clusters[i] == clusters[j] and labels[i] == labels[j]:
                TP += 1
            if clusters[i] == clusters[j] and labels[i] != labels[j]:
                FP += 1
            if clusters[i] != clusters[j] and labels[i] == labels[j]:
                FN += 1
            if clusters[i] != clusters[j] and labels[i] != labels[j]:
                TN += 1

    return (TP + TN) / (TP + FP + FN + TN)