Exercitiul 2 (scrieti va rog un program in pascal) Dau coroana celui ce face corect in pascal!!!

var a:array[1..20,1..20] of integer; n,i,j,s:integer;
begin
readln(n);
for i:=1 to n do
for j=1 to n do
begin
readln(a[i,j]);
if i=j then s:=s+a[i,j]*a[i,j];
end;
writeln(s);
end.