The code seems to solve all matrix multiplication problems on the internet, but fails in one testcase in GUVI (Q no 5 in MATRIX)

def insertinto(matrix, l):
  k = 0
  for i in range(len(matrix)):
    for j in range(len(matrix[0])):
      matrix[i][j] = l[k]
      k += 1
  return matrix

a, b = map(int, input().split())
l1 = list(map(int, input().split()))

c, d = map(int, input().split())
l2 = list(map(int, input().split()))

m1 = [[0 for i in range(b)] for i in range(a)]
m2 = [[0 for i in range(d)] for i in range(c)]

result = [[0 for i in range(d)] for i in range(a)]

m1 = insertinto(m1, l1)
m2 = insertinto(m2, l2)

for i in range(len(m1)):
  for j in range(len(m2[0])):
    for k in range(len(m2)):
      result[i][j] += m1[i][k] * m2[k][j]
for i in result:
  print(*i)

Please let me know if there is any negative testcase, if the provided input is of wrong format...