program ct;

uses crt;

var A:array[1..1000] of integer;

      i,n,k:integer;

begin clrscr;

   write('Nhap so phan tu: '); readln(n);

   for i:=1 to n-1 do

     begin

        write('Nhap A[',i,']: '); readln(A[i]);

     end;

   for i:=1 to n-1 do

     if A[i]<0 then k:=i;

   write('Chi so cua so hang am dau tien cua day la: ',k);

readln;

end.

uses crt;
var n,i,t:longint; a:array[0..10000000]of longint;
begin
clrscr;
   write('n=');readln(n);
   for i:=0 to n-1 do
      begin
         write('a[',i,']=');readln(a[i]);
         if a[i]<0 then t:=i;
      end;
   if t=0 then writeln('Khong co so hang am nao trong day!')
   else writeln('Chi so cua so hang am cuoi cung: ',t);
readln
end.

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Test: