1)
program MQRN;
uses crt;
var N,S,i: longint;
begin
Writeln('Nhap n'); Readln(n);
i:=1; S:=0;
while i<=N do
begin
if (i mod 2)=0 then S:=S+i;
i:=i+1;
end;
Writeln('Tong cac so chan la :',S);
Readln;
end.
2)
program Tim_so_am;
uses crt;
var a: array[1..1000] of integer;
i,N: longint;
begin
Writeln('Nhap so phan tu N: '); Readln(n);
for i:= 1 to n do
begin
Writeln('Nhap so thu ',i); Readln(a[i]);
end;
for i:= 1 to n do if a[i] < 0 then Write(a[i]:5);
Readln;
end.