#You are given a non-empty list of integers (X). For this task, you should return a list 
#consisting of only the non-unique elements in this list. To do so you will need to remove 
#all unique elements (elements which are contained in a given list only once). When solving 
#this task, do not change the order of the list. Example: [1, 2, 3, 1, 3] 1 and 3 non-unique 
#elements and result will be [1, 3, 1, 3].

def checkio(data):
    lista =[]
    for c in data:
        if data.count(c)>1:
            lista.append(c)
    return lista

#Some hints
#You can use list.count(element) method for counting.
#Create new list with non-unique elements
#Loop over original list


if __name__ == "__main__":
    #These "asserts" using only for self-checking and not necessary for auto-testing
    print(checkio([1, 2, 3, 1, 3])) 
    print(checkio([1, 2, 3, 4, 5])) 
    print(checkio([5, 5, 5, 5, 5])) 
    print(checkio([10, 9, 10, 10, 9, 8])) 
#You are given a non-empty list of integers (X). For this task, you should return a list 
#consisting of only the non-unique elements in this list. To do so you will need to remove 
#all unique elements (elements which are contained in a given list only once). When solving 
#this task, do not change the order of the list. Example: [1, 2, 3, 1, 3] 1 and 3 non-unique 
#elements and result will be [1, 3, 1, 3].

def checkio(data):
    lista =[]
    for c in data:
        if data.count(c)>1:
            lista.append(c)
    return lista

#Some hints
#You can use list.count(element) method for counting.
#Create new list with non-unique elements
#Loop over original list


if __name__ == "__main__":
    #These "asserts" using only for self-checking and not necessary for auto-testing
    print(checkio([1, 2, 3, 1, 3])) 
    print(checkio([1, 2, 3, 4, 5])) 
    print(checkio([5, 5, 5, 5, 5])) 
    print(checkio([10, 9, 10, 10, 9, 8])) 
#You are given a non-empty list of integers (X). For this task, you should return a list #consisting of only the non-unique elements in this list. To do so you will need to remove #all unique elements (elements which are contained in a given list only once). When solving #this task, do not change the order of the list. Example: [1, 2, 3, 1, 3] 1 and 3 non-unique #elements and result will be [1, 3, 1, 3]. #Some hints #You can use list.count(element) method for counting. #Create new list with non-unique elements #Loop over original list #These "asserts" using only for self-checking and not necessary for auto-testing