uses crt;
const n = 4;
var a : array [1..n,1..n] of integer;
i, j, s : integer;
begin
clrscr;
randomize;
for i := 1 to n do
for j := 1 to n do
a[i,j] := random(20);
for i := 1 to n do
begin
for j := 1 to n do
begin
write(a[i,j]:3);
end;
writeln;
end;
for i := 1 to n do
for j := 1 to n do
if (i = j) then
s := s + a[i,j];
writeln('Summa = ',s);
readln;
end.