How to compare multiple dictionaries to find out duplicate keys and how many times they are repeated

I need to compare more than 2 dictionaries to find out how many duplicate keys and how many times they are repeated. for example

D1 = {'a' : 'value', 'b': 'value', 'c': 'value', 'd', 'value'}
D2 = {'d', 'value', 'a' : 'value'}
D3 = {'a' : 'value', 'd', 'value', 'b': 'value'}
D4 = {'a' : 'value'}

the output shoule print repeated keys and how many times each key is repeated for example:

4-a # key 'a' is repeated 4 times accross dictionaries
2-b 
3-d

Answer

List Comprehension and then just iterate through array

dic = [x for x in D1] + [x for x in D2] + [x for x in D3] + [x for x in D4]
ans = {} 
for x in dic:
    if x in list:
        ans[x] += 1
    else:
        ans[x] = 1

update
I forgot about dictionary comprehension, so you can shorten that up.

dic = [x for x in D1]+ [x for x in D2] +  [x for x in D3] + [x for x in D4]  
ans = {i:dic.count(i) for i in dic}