uses crt;
const nmax=20;
type matr=array[1..nmax,1..nmax] of integer;
procedure Zamena(var mt:matr;x:byte);
var i,j,k:byte;
begin
if odd(x) then k:=x div 2
else k:=x div 2-1;
for i:=1 to k do
for j:=i+1 to x-i do
mt[i,j]:=0;
end;
var a:matr;
n,i,j:byte;
begin
clrscr;
randomize;
repeat
write('Размер матрицы до ',nmax,' n=');
readln(n);
until n in [1..nmax];
writeln('Исходная матрица:');
for i:=1 to n do
begin
for j:=1 to n do
begin
a[i,j]:=random(50)+1;
write(a[i,j]:4);
end;
writeln;
end;
writeln;
Zamena(a,n);
writeln('Замена элементов выше диагоналей матрицы:');
for i:=1 to n do
begin
for j:=1 to n do
write(a[i,j]:4);
writeln;
end;
readln
end.