def fusion(lst1, lst2):
n1 = len(lst1)
n2 = len(lst2)
lst12 = [0] * (n1 + n2)
i1 = 0
i2 = 0
i = 0
while i1 < n1 and i2 < n2 :
if lst1[i1] < lst2[i2]:
lst12[i] = lst1[i1]
i1 = i1 + 1
else:
lst12[i] = lst2[i2]
i2 = i2 + 1
i += 1
while i1 < n1:
lst12[i] = lst1[i1]
i1 = i1 + 1
i = i + 1
while i2 < n2:
lst12[i] = lst2[i2]
i2 = i2 + 1
i = i + 1
return lst12