différence entre 2 dates (jours)

def biss(a):
    if a % 1000 == 0:
        return True
    elif a % 100 == 0:
        return False
    elif a % 4 == 0:
        return True
    else:
        return False

def ndjdm(m, a):
    x = biss(a)
    m = str(m)
    if x == True:
        Fev = 29
    else:
        Fev = 28
    Dict = {
    "Janvier": 31, "1": 31,
    "Février": Fev, "2": Fev,
    "Mars": 31, "3": 31,
    "Avril": 30, "4": 30,
    "Mai": 31, "5": 31,
    "Juin": 30, "6": 30,
    "Juillet": 31, "7": 31,
    "Aout": 31, "8": 31,
    "Septembre": 30, "9": 30,
    "Octobre": 31, "10": 31,
    "Novembre": 30, "11": 30,
    "Décembre": 31, "12": 31
    }
    return Dict[m]

def temps_entre(a1, m1, j1, a2, m2, j2):
    nbre_j_1 = 0
    nbre_j_2 = 0

    for i in range(0, a1+1):
##        print("Ajout an",i,". Total:",nbre_j_1)
        bis = biss(i)
        if bis == True:
            nbre_j_1 += 366
        else:
            nbre_j_1 += 365
    for i in range (1, m1+1):
##        print("Ajout mois",i,". Total:",nbre_j_1)
        nbre_j_1 += ndjdm(i, a1)
    nbre_j_1 += j1
##    print("Ajout jours. Total:",nbre_j_1)
##    print("Nombre de jours entre 00/01/0000 et",date1,":",nbre_j_1)

    for i in range(0, a2+1):
##        print("Ajout an",i,". Total:",nbre_j_2)
        bis = biss(i)
        if bis == True:
            nbre_j_2 += 366
        else:
            nbre_j_2 += 365
    for i in range (1, m2+1):
##        print("Ajout mois",i,". Total:",nbre_j_2)
        nbre_j_2 += ndjdm(i, a2)
    nbre_j_2 += j2
##    print("Ajout jours. Total:",nbre_j_2)
##    print("Nombre de jours entre 00/01/0000 et",date1,":",nbre_j_2)
    if nbre_j_2 > nbre_j_1:
        return nbre_j_2 - nbre_j_1
    else:
        return nbre_j_1 - nbre_j_2

#-------------------------------------------------------------------------------
date1 = "000000"
date2 = "000000"

while len(date1) != 10 or date1[2] != "/" or date1[5] != "/":
    try:
        date1 = input("Entrez la première date sous la forme XX/XX/XXXX.")
    except:
        date1 = "000000"
while len(date2) != 10 or date2[2] != "/" or date2[5] != "/":
    try:
        date2 = input("Entrez la seconde date sous la forme XX/XX/XXXX.")
    except:
        date2 = "000000"

a1 = int(date1[6] + date1[7] + date1[8] + date1[9])
m1 = int(date1[3] + date1[4])
j1 = int(date1[0] + date1[1])
a2 = int(date2[6] + date2[7] + date2[8] + date2[9])
m2 = int(date2[3] + date2[4])
j2 = int(date2[0] + date2[1])

nbre_j_1 = 0
nbre_j_2 = 0

temps = temps_entre(a1, m1, j1, a2, m2, j2)
print("Il y a",temps,"jours entre le",date1,"et le",date2)