def aparicions(s):
    d = {}
    for c in s:
        if c.isalpha() or c.isdigit():
            if c in d:
                d[c] = d[c] + 1
            else:
                d[c] = 1
    return d

def aparicions_vocals(s):
    d = {vocal: 0 for vocal in 'aeiou'}
    for caracter in s:
        if caracter in d:
            d[caracter] = d[caracter] + 1
    return d