Найти сумму элементов, лежащей на главной диагонали

const n=5;
var a:array[1..n,1..n]of integer;
i,j,min,max,s:integer;
 
begin
 randomize;
 writeln('Ishodnyi massiv: ');
 for i:=1 to n do
 begin
  for j:=1 to n do
  begin
    a[i,j]:=-50+random(100);
    write(a[i,j]:4);
  end;
  writeln;
 end;
 
 max:=a[1,1];
 for i:=1 to n do
 for j:=i to n-1 do if a[i,j]>max then max:=a[i,j];
 writeln('Max element sredi elementov vyshe glav diagonali: ',max);
 
 min:=a[2,2];
 for i:=1 to n do
 for j:=1 to i-1 do if a[i,j]<min then min:=a[i,j];
 writeln('Min element sredi elementov nizhe glav diagonali: ',min);
 
 s:=0;
 for i:=1 to n do s:=s+a[i,i];
 writeln('Summa elementov glavnoi diagonali: ',s);
 readln;
end.

program program_6_1;
uses crt;
var
A: array [1..100, 1..100] of integer;
max,min,i,j,s,N,M: integer;
begin
clrscr;
write ('vvedite N: ');
readln (N);
write ('vvedite M: ');
readln (M);
s:=0;
min:=A[1,1];
max:=A[1,1];
for i:=1 to N do
for j:=1 to M do
begin
write ('vvedite A[',i,',',j,']: ');
readln (A[i,j]);
if j=i
then S:=S+A[i,j];
if (i<j) and (A[i,j]>max)
then max:=A[i,j];
if (i>j) and (A[i,j]<0) and (A[i,j]<min)
then min:=A[i,j]
end;
for i:=1 to N do
 begin
  for j := 1 to N do
    write(a[i,j]:4);
    writeln;
end;
writeln ('Max=',max);
if min<0
then
writeln ('Min=',min)
else writeln ('Ne naiden Min');
writeln ('S=',s);
end.