# http://www.geeksforgeeks.org/find-common-elements-three-sorted-arrays/
def common_elements(input1, input2, input3):
result = []
i = 0
j = 0
k = 0
while i < len(input1) and j < len(input2) and k < len(input3):
if input1[i] == input2[j] and input2[j] == input3[k]:
result.append(input1[i])
i = i + 1
j = j + 1
k = k + 1
elif input1[i] < input2[j]:
i = i + 1
elif input2[j] < input3[k]:
j = j + 1
else:
k = k + 1
return result
if __name__ == '__main__':
input1 = [1, 5, 10, 20, 40, 80]
input2 = [6, 7, 20, 80, 100]
input3 = [3, 4, 15, 20, 30, 70, 80, 120]
print(common_elements(input1, input2, input3))