2 câu trả lời
uses crt;
var i,n,s:longint;
begin
clrscr;
write('Nhap N: ');readln(n);
for i:=1 to n do
if i mod 2=1 then s:=s+i else s:=s-i;
writeln(s);
readln
end.
program ct;
uses crt;
var s,i,n:integer;
begin
s:=1;
for i:=2 to n do s:=s*i;
writeln('tich',s);
readln;
end.