uses crt;
const nmax=20;
var a:array[1..nmax,1..nmax] of byte;
n,i,j:byte;
begin
clrscr;
repeat
write('Размер матрицы=');
readln(n);
until n in [1..nmax];
writeln('Исходная матрица:');
for i:=1 to n do
begin
for j:=1 to n do
begin
if i=j then a[i,j]:=1
else if j<i then a[i,j]:=0
else a[i,j]:=i+j;
write(a[i,j]:4);
end;
writeln;
end;
readln
end.