program PascalGuru;
label 1;
var A:array[1..100,1..100] of integer; {переменная массива}
    i,j,n:integer; {переменные для циклов}
 
{------------------------------------}
procedure exchange(var a,b:integer);
var c:integer;
begin
c:=a; a:=b; b:=c; end;
{------------------------------------}
 
begin
1:write ('Vvedite razmer matricy A: ');
readln (n);
 
if n<4 then
   begin
   writeln('N doljno byti bolishe 4!');
   writeln;
   goto 1;
   end;
 
 
for i:=1 to n do
for j:=1 to n do begin
write ('A[',i,',',j,']='); readln (A[i,j]); end;
 
write ('Vot vvedennai vami matrica A: ');
for i:=1 to n do begin writeln;
for j:=1 to n do write (A[i,j]:8); end;
 
 
for j:=1 to n do exchange (A[1,j],A[3,j]);
for j:=1 to n do exchange (A[2,j],A[4,j]);
 
 
writeln; writeln;
write ('Vot PREOBRAZOVANNAYA matrica A: ');
for i:=1 to n do begin writeln;
for j:=1 to n do write (A[i,j]:8); end;
 
 
readln;
end.