Uses crt;
const n=5; m=4;
var
b,a:array[1..n,1..m] of integer;
str:array[1..m] of integer;
buf,i,j:integer;
begin
randomize;
clrscr;
for i:=1 to n do
begin
for j:=1 to m do
begin
a[i,j]:=random(50);
a[i,j]:=a[i,j]-50;
write(a[i,j]:4);
end;
writeln;
end;
for i:=1 to n do
for j:=1 to m do
b[i,j]:=a[i,j];
writeln;
for i:=1 to n do
for j:=1 to 3 do
b[i,j]:=abs(b[i,j]);
for i:=1 to n do
begin
for j:=1 to m do
write(b[i,j]:4);
writeln;
end;
writeln;
for j:=1 to m do
a[4,j]:=a[2,j];
for i:=1 to n do
begin
for j:=1 to m do
write(a[i,j]:4);
writeln;
end;
writeln;
for j:=1 to m do
begin
buf:=a[2,j];
a[2,j]:=a[n,j];
a[n,j]:=buf;
end;
for i:=1 to n do
begin
for j:=1 to m do
write(a[i,j]:4);
writeln;
end;
readkey;
end.