輸入
list1 = [1,2,3,3,3]
list2 = [1,2,3]
輸出
[3,3]

list1 = [1,2,3,3,3]
list2 = [1,2,3]
s_scaned = []
diff = []
for s in list1:
    if s in s_scaned:
        continue
        
    s_scaned.append(s)
    
    if s not in list2:
        diff.append(s)
    else:
        l1_num = list1.count(s)
        l2_num = list2.count(s)
        if l1_num > l2_num:
            for i in range(l1_num - l2_num):
                diff.append(s)
print diff