def equal(arr):
    # Write your code here
    arr.sort()
    arr_len = len(arr)
    diff_table = [0]*arr_len
    for i in range(1, arr_len):
        # acumulate diff
        diff_table[i] = diff_table[i-1] + arr[i] - arr[i-1]
        
    final_ans = [float('inf')]

    def caculate_ans(add_val, final_ans):
        ans = 0
        if add_val != 0:
            ans += 1

        for i in range(1, arr_len):
            # acumulate diff
            cur_diff = diff_table[i] + add_val
            ans += cur_diff//5
            cur_diff = cur_diff%5
            ans += cur_diff//2
            cur_diff = cur_diff%2
            ans += cur_diff//1
            cur_diff = cur_diff%1
        final_ans[0] = ans if ans < final_ans[0] else final_ans[0]
    # we can add 1, 2 or 5 equally to diff_table from index 1 to arr_len (add all but index 0)
    caculate_ans(0, final_ans)
    caculate_ans(1, final_ans)
    caculate_ans(2, final_ans)
    caculate_ans(5, final_ans)

    return final_ans[0]