def hardness(s: str) -> float:
    """Get the element hardness."""
    d = {
        'h': 6.4299, 'he': 12.5449, 'li': 2.3746, 'be': 3.4968, 'b': 4.619, 'c': 5.7410,
        'n': 6.8624, 'o': 7.9854, 'f': 9.1065, 'ne': 10.2303, 'na': 2.4441, 'mg': 3.0146,
        'al': 3.5849, 'si': 4.1551, 'p': 4.7258, 's': 5.2960, 'cl': 5.8662, 'ar': 6.4366,
        'k': 2.3273, 'ca': 2.7587, 'sc': 2.8582, 'ti': 2.9578, 'v': 3.0573, 'cr': 3.1567,
        'mn': 3.2564, 'fe': 3.3559, 'co': 3.4556, 'ni': 3.555, 'cu': 3.6544, 'zn': 3.7542,
        'ga': 4.1855, 'ge': 4.6166, 'as': 5.0662, 'se': 5.4795, 'br': 5.9111, 'kr': 6.3418,
        'rb': 2.1204, 'sr': 2.5374, 'y': 2.6335, 'zr': 2.7297, 'nb': 2.8260, 'mo': 2.9221,
        'tc': 3.0184, 'ru': 3.1146, 'rh': 3.2107, 'pd': 3.3069, 'ag': 3.4032, 'cd': 3.4994,
        'in': 3.9164, 'sn': 4.3332, 'sb': 4.7501, 'te': 5.167, 'i': 5.5839, 'xe': 6.0009,
        'cs': 0.6829, 'ba': 0.9201, 'la': 1.1571, 'ce': 1.3943, 'pr': 1.6315, 'nd': 1.8686,
        'pm': 2.1056, 'sm': 2.3427, 'eu': 2.5798, 'gd': 2.8170, 'tb': 3.0540, 'dy': 3.2912,
        'ho': 3.5283, 'er': 3.7655, 'tm': 4.0026, 'yb': 4.2395, 'lu': 4.4766, 'hf': 4.7065,
        'ta': 4.9508, 'w': 5.1879, 're': 5.4256, 'os': 5.6619, 'ir': 5.900, 'pt': 6.1367,
        'au': 6.3741, 'hg': 6.6103, 'tl': 1.7043, 'pb': 1.9435, 'bi': 2.1785, 'po': 2.4158,
        'at': 2.6528, 'rn': 2.8899, 'fr': 0.9882, 'ra': 1.2819, 'ac': 1.3497, 'th': 1.4175,
        'pa': 1.9368, 'u': 2.2305, 'np': 2.5241, 'pu': 3.0436, 'am': 3.4169, 'cm': 3.4050,
        'bk': 3.9244, 'cf': 4.2181, 'es': 4.5116, 'fm': 4.8051, 'md': 5.0100, 'no': 5.3926,
        'lr': 5.4607}
    return d[s] / 27.211