# coding: UTF-8
import copy
def jun(arr):
    for e1 in arr:
        p1 = e1
        arr1 = copy.copy(arr)
        arr1.remove(e1)
        for e2 in arr1:
            p2 = p1 + e2
            arr2 = copy.copy(arr1)
            arr2.remove(e2)
            for e3 in arr2:
                p3 = p2 + e3
                arr3 = copy.copy(arr2)
                arr3.remove(e3)
                for e4 in arr3:
                    p4 = p3 + e4
                    print(p4)
 
arr = ["A","B","C","D"]
jun(arr)
 

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