def common_argument(M):
    element = M[0][4]
    for i in range(len(M)):
        if M[i][4] != element:
            if period(M, element) < period(M, M[i][4]):
                element = M[i][4]
    return element



 def period(M,c):
        s = 0
        for i in range(len(M)):
            if c in M[i]:
                if M[i][2] != M[i][3]:
                     if M[i][2] > M[i][3]:
                         s += M[i][2] - M[i][3]
                     if M[i][3] > M[i][2]:
                         s += M[i][3] - M[i][2]
         return s


    common_argument([[10, 1, 15, 17, 'Vendite'],
    [10, 1, 17, 18, 'Progetti'],
    [16, 2, 10, 12, 'Vendite'],
    [16, 2, 13, 15, 'Progetti'],
    [5,3,10, 13, 'Progetti']])