写一个程序：根据从键盘输入的n的值，显示螺旋式数字方阵。

program t23_3;
const
u=100;
var
a:array[0..u,1..u]of integer;
n,k,i,j:integer;

procedure print;
begin
inc(k);
a[i,j]:=k;
if k=n*n then
begin
for i:=1 to n do
begin
for j:=1 to n do
write(a[i,j]:4);
writeln;
end;
readlln;halt
end;
Begin
writeln('Input n');
read(n);
fillchar(a,sizeof(a),0);
for j:=1 to n do
a[0,j]:=100;
k:=1; i:=1; j:=1; a[i,j]:=1;
Repeat
repeat
inc(i);
print;
until (i=n)or(a[i+1,j]<>0);
repeat
inc(j);
print;
until (j=n)or(a[i,j+1]<>0);
repeat
dec(i);
print;
until (a[i-1,j]<>0);
repeat
dec(j);
print;
until (a[i,j-1]<>0)