l~/{_1fb_,Y${(_@=}%:++z}2*;=

4 [1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16]

l~/                               "Evaluates the input and split the array into chunks"
                                  "of size N where N is the first integer";
   {                      }2*     "Run this code block 2 times";
    _1fb                          "Copy the 2D array and calculate sum of each row of copy";
        _,                        "Copy the array containing sum of each row and get"
                                  "its length. This is equal to N";
          Y${      }%             "Run this code block for each array of the original"
                                  "2D array that we copied from stack";
             (_                  "Put the length number to top of stack, decrement and"
                                  "copy that";
                @=               "Take the element at that index from each row and put"
                                  "N back behind at second position in stack";
                     :+           "Take sum of elements of the array. This is sum of"
                                  "one of the diagonals of the 2D array";
                       +          "Push diagonal sum to row sum array";
                        z        "Bring original array to top and transpose columns";
                             ;    "At this point, the stack contain 3 arrays:"
                                  "  Array with sum of rows and main diagonal,"
                                  "  Array with sum of columns and secondary diagonal and"
                                  "  The original array. Pop the original array";
                              =   "Check if sum of rows + main diagonal array is equal to ";
                                  "sum of columns + secondary diagonal array";

STDIN: 4,[16,3,2,13,5,10,11,8,9,6,7,12,4,15,14,1]
Output: True

∧/2=/(+⌿x,⍉x),+/↑1 1∘⍉¨x(⌽x←⎕⍴⍨,⍨⎕)

d = Diagonal; r = Reverse; i = Input[];
Length@Union[Tr /@ Join[p = Partition[i[[2]], i[[1]]],
t = Transpose@p, {d@p}, {d@t}, {d@r@p}, {d@r@t}]] == 1

{4,{16, 3, 2, 13, 5, 10, 11, 8, 9, 6, 7, 12, 4, 15, 14, 1}}

∧/2=/+⌿(1 1∘⍉∘⌽,1 1∘⍉,⍉,⊢)⎕⍴⍨,⍨⎕

{M←⍺ ⍺⍴⍵⋄d←M=⍉M⋄(⊃≡∪)((+/,+⌿)M),+/∘,¨d(⌽d)ר⊂M}

4{M←⍺ ⍺⍴⍵⋄d←M=⍉M⋄(⊃≡∪)((+/,+⌿)M),+/∘,¨d(⌽d)ר⊂M}16 3 2 13 5 10 11 8 9 6 7 12 4 15 14 1
1

~]:q(/q(/zip+[q()/{(;}%]+[q((/);(;{(;}%]+{{+}*}%.&,2<q(2?,{)}%-!*

s=io.read(1)v=io.read(2)d=0 r=0 for i=1,#s do t=0 for j = 1, #s do t=t+s[i][j]end d=d+s[i][i] r=r+s[i][#s-i+1]if t ~= v then o=true end end if d~=v and r~= v then o=true end print(not o)

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