# Write a Python program to Count the frequency of matrix row length 
 # Python3 code to demonstrate working of
# Row lengths counts
# Using dictionary + loop
  
# initializing list
test_list = [[6, 3, 1], [8, 9], [2], 
             [10, 12, 7], [4, 11]]
  
# printing original list
print("The original list is : " + str(test_list))
  
res = dict()
for sub in test_list:
  
    # initializing incase of new length
    if len(sub) not in res:
        res[len(sub)] = 1
  
    # increment in case of length present
    else:
        res[len(sub)] += 1
  
# printing result
print("Row length frequencies : " + str(res))