Program Snake;
Uses CRT;
Const m = 4;
Var Count: Integer;
     i: Byte;
     ii: Byte;
     a: Array[1..m, 1..m] of Integer;

Procedure Print;
Var j, jj: Byte;
Begin
ClrScr;
For j := 1 to m do
     Begin
     For jj := 1 to m do
         Write(a[j,jj]:3);
     Writeln;
     End;
ReadKey;
End;

Begin
ClrScr;
Count := 1;
i := 1;
a[1,1] := 1;
Print;
While (Count <> m * m) do
       Begin
       Inc(i);
       If (i <= m) then
       If (Odd(i)) then For ii := i downto 1 do
                            Begin
                            Inc(Count);
                            a[ii,i-ii+1] := Count;
                            Print;
                            End
                   else For ii := i downto 1 do
                            Begin
                            Inc(Count);
                            a[i-ii+1,ii] := Count;
                            Print;
                            End
       else
       If (not Odd(i)) then For ii := i-m+1 to m do
                            Begin
                            Inc(Count);
                            a[ii,m-ii+(i-m+1)] := Count;
                            Print;
                            End
                   else For ii := i-m+1 to m do
                            Begin
                            Inc(Count);
                            a[m-ii+(i-m+1),ii] := Count;
                            Print;
                            End;
       End;
End.