program tong;
uses crt;
var i,n,tong: integer;
  a:array[1..50] of integer;
begin 
write(' nhap do dai day so: '); read(n);
tong:=0;
for i:=1 to n do
begin
 write(' nhap gia tri cua mang: '); read(a[i]);
 write(' a[',i,']=', a[i])
 if a[i]<0 then tong:=tong+a[i];
end;
write(' tong cua cac phan tu am la: ',tong);
readln;
end.
check giùm mk có sai thì sửa lại nhen :D