给定一个二维整数数组。 按照主对角线上元素的降序重新排列其中的线。萌新，求问一下红色部分怎么解决，还有其他的问题吗，求教求教求教

program Project1;
uses crt;
const N0=100;
Var A:Array[1..N0,1..N0]Of integer;
M:lnteger;
i,j,k,B:Byte;
begin
Repeat
Write('N=');
Read(N);
Until(N in [1..100]);
Randomize;
For i:=1 To N Do
begin
For j:=1 To N Do
begin
A[i,j]:=Random(100);
Write(A[i,j]:4);
End;
WriteLn;
End;
writeln;
For i:=1 To N-1 Do
For j:=i+1 To N Do
if(A[i,n-i+1]>A[j,n-j+1])Then
begin
M:=A[i,n-i+1];
A[i,n-i+1]:=A[j,n-j+1];
A[j,n-j+1]:=M;
End;
For i:=1 To N Do
begin
For j:=1 To N Do
Write(A[i,j]:4);
WriteLn;
End;
end.